The Parts of a Leaf The Parts of a Leaf Most leaves have two main parts: (1) the blade and (2) the petiole, or leafstalk. The leaves of some kinds of plants also have a third part, called the stipules. The Blade, or lamina, is the broad, flat part of the leaf. Photosynthesis occurs in the blade, which has many green food-making cells. Leaf blades differ from one another in several ways: (1) the types of edges, (2) the patterns of the veins, and (3) the number of blades per leaf. The Types of Edges. Almost all narrow, grasslike leaves and needles leaves have a blade with a smooth edge, as do many broadleaf plants, particularly those that are native to warm climates. The rubber plant, a common house plant, is a good example of such a plant. The leaves of many temperate broadleaf plants have small, jagged points called teeth along the blade edge. Birch and elm trees have such leaves. Some plants have hydathodes, tiny valvelike structures that can release excess water from the leaf.

The teeth of young leaves on many plants, including cottonwood and pin cherry trees, bear tiny glads. These glands produce liquids that protect the young leaf from plant-eating insects. Some temperate broadleaf plants -- including sassafras trees and certain mulberry and oak trees -- have lobed leaves. The edge of such a leaf looks as if large bites have been taken out of it. This lobing helps heat escape from the leaf. The Patterns of the Veins. Veins carry food and water in a leaf. They also support the blade, much as the metal ribs support the fabric of an open umbrella. In most broad leaves, the veins form a netlike pattern, with several large veins connected by smaller ones. The smallest veins supply every part of the blade with water. They also collect the food made by the green cells. There are two main types of net-vein patterns -- pinnate (featherlike) and palmate (palmlike or handlike). Pinnately veined leaves have one large central vein, called the midrib, which extends from the base of the blade to its tip. Other large veins branch off on each side of the midrib.

The leaves of beech, birch, and elm trees have such a vein pattern. A palmately veined leaf has several main veins of about equal size, all of which extend from a common point at the base of the blade. The vein patterns of maple, sweet gum, and sycamore leaves are palmate. Narrow leaves and needle leaves are not net-veined. Narrow leaves have a parallel-vein pattern. Several large veins run alongside one another from the base of the blade to the tip. Small crossveins connect the large veins. Needle leaves are so small that they have only one or two veins running through the center of the blade. The Number of Blades per Leaf. A leaf with only one blade is called a simple leaf. Apple and oak trees, grasses, and many other plants have simple leaves. A leaf with more than one blade is known as a compound leaf. The blades of a compound leaf are called leaflets. The leaflets in a compound leaf may be arranged in a pinnate or palmate pattern. In pinnately compound leaves, the leaflets grow in two rows, one on each side of a central stalk, called the rachis.

Plants with pinnately compound leaves include ash and walnut trees and garden peas. The leaflets in a palmately compound leaf all grow from the tip of the leafstalk. Clover, horse chestnut trees, and many other plants have palmately compound leaves. A few plants -- including carrots, honey locust trees, and Kentucky coffeetrees -- have double compound leaves, with each leaflet being divided into a number of still smaller leaflets.One double compound leaf looks more like a group of twigs and leaves than like a single leaf. The Petiole is the stemlike part of the leaf that joins the blade to the stem. Within a petiole are tiny tubes that connect with the veins in the blade. Some of the tubes carry water into the leaf. Others carry away food that the leaf has made. In many trees and shrubs, the petioles bend in such a way that the blades receive the most sunlight, thus assuring that few leaves are shaded by other leaves. The petiole also provides a flexible "handle" that enables the blade to twist in the wind and so avoid damage. In some plants, the petioles are much larger than the stems to which they are attached.

For example, the parts we eat of celery and rhubarb plants are petioles. In contrast, the leaves of some soft-stemmed plants, particularly grasses, have no petioles. The Stipules are two small flaps that grow at the base of the petiole of some plants. In some plants, the stipules grow quickly, enclosing and protecting the young blade as it develops. Some stipules, such as those of willows and certain cherry trees, produce substances that prevent insects from attacking the developing leaf. In many plants the stipules drop off after the blade has developed, but garden peas and a few other kinds of plants have large stipules that serve as an extra food-producing part of the leaf. World Book Encyclopedia Chicago: World Book-Childcraft International, Inc., 1979 Leaf - body, used, water, process, plants, chemical, form, reaction, carbon Leaf Leaf Photo by: Subbotina Anna A leaf is a plant's principal organ of photosynthesis, the process by which sunlight is used to form foods from carbon dioxide and water. Leaves also help in the process of transpiration, or the loss of water vapor from a plant.

A typical leaf is an outgrowth of a stem and has two main parts: the blade (flattened portion) and the petiole (pronounced PET-ee-ole; the stalk connecting the blade to the stem). Some leaves also have stipules, small Bay laurel leaves. (Reproduced by permission of Field Mark Publications .) paired outgrowths at the base of the petiole. Scientists are not quite sure of the function of stipules. Leaf size and shape differ widely among different species of plants. Duckweeds are tiny aquatic plants with leaves that are less than 0.04 inch (1 millimeter) in diameter, the smallest of any plant species. Certain species of palm trees have the largest known leaves, more than 230 feet (70 meters) in length. Words to Know Abscission layer: Barrier of special cells created at the base of petioles in autumn. Blade: Flattened part of a leaf. Chloroplasts: Small structures that contain chlorophyll and in which the process of photosynthesis takes place. Margin: Outer edge of a blade. Midrib: Single main vein running down the center of a blade.

Petiole: Stalk connecting the blade of a leaf to the stem. Phloem: Plant tissue consisting of elongated cells that transport carbohydrates and other nutrients. Photosynthesis: Process by which a plant uses sunlight to form foods from carbon dioxide and water. Stomata: Pores in the epidermis of leaves. Transpiration: Evaporation of water in the form of water vapor from the stomata. Xylem: Plant tissue consisting of elongated cells that transport water and mineral nutrients. Leaf arrangement A leaf can be classified as simple or compound according to its arrangement. A simple leaf has a single blade. A compound leaf consists of two or more separate blades, each of which is termed a leaflet. Each leaflet can be borne at one point or at intervals on each side of a stalk. Compound leaves with leaflets originating from the same point on the petiole (like fingers of an outstretched hand) are called palmately compound. Compound leaves with leaflets originating from different points along a central stalk are called pinnately compound. All leaves, no matter their shape, are attached to the stem in one of three ways: opposite, alternate, or whorled.

Opposite leaves are those growing in pairs opposite or across from each other on the stem. Alternate leaves are attached on alternate sides of the stem. Whorled leaves are three or more leaves growing around the stem at the same spot. Most plant species have alternate leaves. Blade The outer edge of a blade is called the margin. An entire margin is one that is smooth and has no indentations. A toothed margin has small or wavy indentations. A lobed margin has large indentations (called sinuses) and large projections (called lobes). A scanning electron micrograph of open stomata on the underside of a rose leaf. Stomata are breathing pores scattered over the leaf surface that regulate the exchange of gases between the leaf's interior and the atmosphere. (Reproduced by permission of Photo Researchers, Inc. ) Venation is the pattern of veins in the blade of a leaf. A single main vein running down the center of a blade is called a midrib. Several main veins are referred to as principle veins. A network of smaller veins branch off from a midrib or a principle vein. All veins transport nutrients and water in and out of the leaves.

The two primary tissues in leaf veins are xylem (pronounced ZY-lem) and phloem (pronounced FLOW-em). Xylem cells mainly transport water and mineral nutrients from the roots to the leaves. Phloem cells mainly transport carbohydrates (made by photosynthesis) from the leaves to the rest of the plant. Typically, xylem cells are on the upper side of the leaf vein and phloem cells are on the lower side. Internal anatomy of leaves Although the leaves of different plants vary in their overall shape, most leaves are rather similar in their internal anatomy. Leaves generally consist of epidermal tissue on the upper and lower surfaces and mesophyll tissue throughout the body. Epidermal cells have two features that prevent the plant from losing water: they are packed densely together and they are covered by a cuticle (a waxy layer secreted by the cells). The epidermis usually consists of a single layer of cells, although the specialized leaves of some desert plants have epidermal layers that are several cells thick. The epidermis contains small pores called stomata, which are mostly found on the lower leaf surface.

Each individual stoma (pore) is surrounded by a pair of specialized guard cells. In most species, the guard cells close their stomata during the night (and during times of drought) to prevent water loss. During the day, the guard cells open their stomata so they can take in carbon dioxide for photosynthesis and give off oxygen as a waste product. The mesophyll layer is divided into two parts: palisade cells and spongy cells. Palisade cells are densely packed, elongated cells lying directly beneath the upper epidermis. These cells house chloroplasts, small structures that contain chlorophyll and in which the process of photosynthesis takes place. Spongy cells are large, often odd-shaped cells lying underneath palisade cells. They are loosely packed to allow gases (carbon dioxide, oxygen, and water vapor) to move freely between them. Leaves in autumn Leaves are green in summer because they contain the pigment chlorophyll, which absorbs all the wavelengths of sunlight except for green (sunlight or white light comprises all the colors of the visible spectrum: red, orange, yellow, green, blue, indigo, and violet).

In addition to chlorophyll, leaves contain carotenoid (pronounced kuh-ROT-in-oid) pigments, which appear orange-yellow. In autumn, plants create a barrier of special cells, called the abscission (pronounced ab-SI-zhen) layer, at the base of the petiole. Moisture and nutrients from the plant are cut off and the leaf begins to die. Chlorophyll is very unstable and begins to break down quickly. The carotenoid pigments, which are more stable, remain in the leaf after the chlorophyll has faded, giving the plant a vibrant yellow or gold appearance. The red autumn color of certain plants comes from a purple-red pigment known as anthocyanin (pronounced an-tho-SIGH-a-nin). Unlike carotenoids, anthocyanins are not present in a leaf during the summer. They are produced only after a leaf starts to die. During the autumn cycle of warm days and cool nights, sugars remaining in the leaf undergo a chemical reaction, producing anthocyanins.

Tomato Leaf Anatomy cross section of leaf midrib cross section of leaf (p-palisade mesophyll, s-spongy mesophyll) Most leaves are protected by a thin outer cuticle. Just inside the cuticle lies the epidermis. Note that the epidermis surrounds the leaf and is therefore visible on the abaxial (lower) and adaxial (upper) sides of the leaf in cross section. The epidermis contains stomata. Note the stoma on the abaxial side of the leaf in the cross section on the right. For more information about stomata please scroll down. In the center of the leaf lies the mesophyll. The mesophyll consists of two different cell types. Palisade mesophyll is composed of oblong, upright parenchyma cells. Spongy mesophyll consists of more irregularly shaped parenchyma cells arranged in a loose structure. Most of the plant's photosynthesis takes place in the mesophyll of the leaf. Midrib cross section through leaf midrib with polarized light The leaf contains many vascular bundles distributed in veins throughout the leaf. The leaf's main vein runs through the midrib. Typical plants have leaves with collateral bundles.

The xylem is on the adaxial side of the vascular bundle, while the phloem is on the abaxial side of the bundle. In contrast, tomato leaves, like the tomato petiole, have bicollateral bundles. The xylem is in the center of the vein with the phloem distributed on both the adaxial and abaxial sides of the bundle (Hayward 1938). For more information about leaf venation please scroll down. Veins This diagram shows a partial venation pattern. leaf clearing The leaf's vascular bundles are arranged in veins that run throughout the leaf. The tomato leaf exibits reticulate venation. This form of venation is common in dicotyledon leaves. The midvein runs through the midrib and is the main vascular bundle in the leaf. Lateral veins branch off of the midvein. These veins continue to branch, becoming smaller and smaller. These smaller veins eventually will either meet to form small boxes called areoles, or they will terminate leaving a free bundle end. In reticulate venation no cell is more than six cells away from a vascular bundle.

If you are interested in further information about venation and would like to see more leaf clearings click on Venation Patterns Stomata epidermal peel All gaseous exchange occurs through the stomata. The leaf epidermis contains many stomata. The stoma's opening, or aperture, is controlled by the two guard cells. The guard cells change shape to open and close the aperture. Surrounding the guard cells are subsidiary cells. Below the epidermis lies a substomatal chamber where the parenchyma cells form an air space. Connect to the Stomata page if you would like to see an enlarged version of this epidermal peel and are interested in more information about stomata. Trichomes Trichomes occur in the epidermis of many plants. Trichomes are abundant in tomato plants. Here we see two types of trichomes found in tomato, multicellular hairs and glandular trichomes. The glandular trichomes are responsible for secreting a yellow substance that gives off that characteristic "tomato plant" smell. Midrib | Define Midrib at Dictionary.com midrib the central or middle rib of a leaf.

Origin of midrib Examples from the Web for midrib Expand Historical Examples Most of the lobes are attached to the wing of the midrib by a broad base: the lower ones sometimes have a short stalk. Beautiful Ferns Daniel Cady Eaton Wire must also be laid on all the side ribs or veins leading to the midrib. Vegetable Teratology Maxwell T. Masters The veins, and notably the midrib of the limb of the sepals, united underneath. Everyday Objects W. H. Davenport Adams There are several big ribs starting at the same place instead of one midrib. Ethel Morton's Enterprise Mabell S.C. Smith It differs from Delesseria alata in having no midrib or veins. Botany - Leaves Botany - Leaves A.ï¿½ A leaf consists of a ____________________________________ and a _______________________________________. 1.ï¿½ The petiole ï¿½ 2.ï¿½ The blade ï¿½ e.g. Maple treeï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ e.g.

Pecan treeï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ e.g. Mimosa or Mesquite trees 3.ï¿½ Leaves without petioles are called _______________________. 4.ï¿½ Some leaves have appendages called __________________at the base of the petiole. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ B. ___________________________- vascular bundles in the blade of the ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ leaf. Types of venation: 1.

_____________________________- large veins originate at the ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ base of the blade but run parallel to each other along the length of ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ the blade ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 2.

___________________________- secondary veins branch from ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ the main vein (midrib) running along the center of the leaf (dicots) ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 3. _____________________________- large veins fan out from the ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ base of the blade (dicots) ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 4.

____________________________- small veins fork evenly from ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ the base of the blade (primitive trees like Ginkgo) e.g.

maple trees Ginkgo trees ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ C.ï¿½ Leaf Margins ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1.ï¿½ ________________________ ï¿½ an undivided & unserrated leaf ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 2.ï¿½ ________________________ - having a notched or sawlike ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï

¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ edge 3.ï¿½ ________________________ ï¿½ lobed towards the midrib but not reaching it 4.ï¿½ ________________________ ï¿½ having a wavy outline or appearance 5.ï¿½ ________________________ ï¿½ scalloped or round-toothed 2.ï¿½ Compound leaves- blade is divided into __________________ on one petiole.ï¿½ There are 3 basic types of compound leavesï¿½ ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ a.

Palmate - ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ b. Pinnate - ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ c. Bipinnate- E. __________________ - arrangement of leaves on the stem. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1.

Alternate- ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 2. Opposite- ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 3. Whorled- ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 4. Spiral- ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ A.

Leaves originate as ____________________________________ fromï¿½ meristematic tissues. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ B. __________________________- the top and bottom surfaces of a leaf ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ are covered with epidermis.

ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1.ï¿½ A __________________________ to prevent water loss usually ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ covers the epidermis. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 2.

Gas exchange occurs through openings called ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ _______________________________________ (stoma/stomata). ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ a.

Each stomata is opened and closed by ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ______________________________________. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ b.ï¿½ Guard cells have chloroplasts.

ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 3. Epidermis may also contain glands and leaf hairs. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ C.

___________________________- the body of the leaf is composed of ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ mesophyll tissue of two types: palisade mesophyll and spongy mesophyll ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1.ï¿½ The mesophyll carries out __________________________ ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 2.ï¿½ The mesophyll is composed of chlorenchyma tissue ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿

½ï¿½ï¿½ï¿½ï¿½ï¿½ a.ï¿½ Chlorenchyma tissue is parenchyma with chloroplasts 3.

Most monocots do not differentiate their mesophyll into spongy ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ and palisade layers. D. __________________________- extensions of the vascular tissue of the stem ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1. ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 2. ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 3. Vascular bundles are surrounded by the ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ________________________________ (parenchyma cells) a. In C3 plants, the bundle sheath cells usually do not contain chloroplasts. b.

In C4 plants, the bundle sheath cells usually do have chloroplasts. A. Shade leaves- usually thinner and with fewer leaf hairs than sun leaves. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1.ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ B. Arid regions leaves- in general, plants tend to have the following characteristics: ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1. ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 2. ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 3.

ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 4. ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 5. ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 6. Succulent leavesï¿½hold water ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 7. Hypodermisï¿½ 1.ï¿½ Spines are modified ___________________________ (cactus). 2.ï¿½ Thorns are modified _________________________(mesquite). 3.ï¿½ Prickles are modified epidermal or cortex cells (roses, raspberries). E. Storage Leaves- succulent leaves ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1.

Store water in dry environments ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 2. Some are modified for food storage (onions, lilies) F. ï¿½Flower Potï¿½ leaves- cup-like leaves found in some species of Dischidia (found in Australia).ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1.ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 2.ï¿½ G. Window leaves- buried leaves with a transparent layer that allows sunlight in. The photosynthetic cells are buried in the ground. Adaptation to dry, sandy climates. H. Reproductive leaves- leaves that can develop into new plants. ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1.

When broken off, they develop into adventitious roots and stems. J. Insect Trapping Leaves- found on insectivorous plants, which use insect tissues as aï¿½ source of _________________________________. 1. e.g. K.ï¿½ __________________________________ (motor) leaves ï¿½ Common in monocots (especially grasses), bulliform cells are thin-walled cells on either side of the main central vein (midrib).ï¿½ Under ______________________, the bulliform cells partly _____________________.ï¿½ The collapse causes the leaf to fold or roll, reducing transpiration.ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1.ï¿½ They also probably play a role in the unfolding of developing ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ leaves. Watch this video of the Fainting Mimosa (also called a Touch-Me-Not plant). IV.

Leaf Senescence and Abscission ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ A. ____________________________________ - Color Changes ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1. Most deciduous trees and many perennial herbs have leaves ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ that change from green to yellow, orange, or red in the fall. ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 2.

The non-green colors are due toï¿½ a.ï¿½ Carotenes (________________________________) ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ b.ï¿½ Xanthophylls (________________________________) c.ï¿½ Anthocyanins (______________________________) and d.ï¿½ Betacyanins (________________________________). ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 3. These pigments are always present but are masked by ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ________________________________. a.ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ B.

____________________________________- dropping of leaves ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 1. Occurs at the abscission cells zone near the base of each ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ petiole. 2. Hormones inhibit the formation of abscission cells during the growth of young leaves. 3.ï¿½ As the leaf ages, hormonal changes occur, and at least two layers of cells differentiate into the ___________________________________and the a. The protective layer is several cells deep and highly suberized. 1) It protects the rest if the plant from invasion and water loss when the leaf drops. b.

The separation layer contains cells that produce a lot of pectin. ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 4. Certain environmental cues (temperature, day length) cause the ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ activation of enzymes that degrade the pectin, causing the lamellae ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ to separate. a.ï¿½ A few strands of xylem still hold the leaf, but wind or rain easily breaks them. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 5. ________________________________- drop leaves seasonally ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ 6.

__________________________________ also drop leaves, but ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ not all at once. Parts of a leaf To know more about "The leaves" Parts of a leaf THE LEAF: FUNCTIONS What is a leaf? A leaf is a vegetative part of the plant. It generally has a flat form and a thin surface. The leaf is one of the most important part of the plants because it is the one which is in charge of accomplishing the photosynthesis , the respiration and transpiration. The leaf: parts There are different types of leaves, which let us to distinguish the different kinds of plants, but essentially, each leaf is formed by the following parts: B) Petiole The blade is the expanded part of the leaf. It is the most conspicuous part, what most of people identify and understand as a leaf when such a noun is mentioned. Different types of blade Inside the blade the following parts can be distinguished: - The veins : are a like wrinkles or pipes running along the blade. They are really the vascular bundles coming from the stem throughout the petiole into the the surface of the blade.

The central vein is called Midrib. The different patters they draw in different species is a trait used by botanists to distinguish a plant from the other. - The margin is the rim or final limit of the blade. It can offer different forms: Different types of margin - The petiole is the connexion of the stem to the blade. It is the channel for the vascular bundles to arrive to it. It can be short or long. Those leaves having a petiole, no matter how long it may be, are called petiolated. There are some leaves without petiole. In this case they are called stalkless or sessile. A petiolated leaf and a stalkless one Weed Identification — Center for Turfgrass Science — Penn State University Share Weed Identification To identify weeds you must first distinguish between broadleaf weeds and grass weeds. Broadleaf weeds usually have wider leaf blades than grass weeds. Each leaf typically has a main vein that divides the leaf in half with a network of smaller veins (originating from the main vein) forming a netlike pattern. Broadleaf weeds have distinct leaf shapes and surface characteristics that can be used in identification. The arrangement of leaves on stems can also be a useful identification aid.

Leaves either are alternately arranged (when a leaf grows from a node on one side of the stem and another is produced on the opposite side further up the stem) or arranged opposite one another. Some broadleaf weeds produce leaves in a circular pattern (rosette) from a central growing point located at or beneath the soil surface. Others grow and spread by means of creeping aboveground stems called stolons or belowground stems called rhizomes. Broadleaf weeds can produce a fibrous root system or a root system dominated by a large, fleshy taproot. Broadleaf weeds often bear colorful flowers of different sizes and shapes. At certain times of the year flowers can be very useful identification aids. Grass weeds have long, narrow leaves with veins running parallel to each other (they do not form a netlike pattern). Grasses do not have showy or colorful flowers, and leaf shapes are similar among species. The ability to identify grasses depends on recognizing growth habits, certain vegetative features, and seedheads. Growth habits of grasses Growth habits of grasses can be divided into three different categories: bunch-type, rhizomatous, and stoloniferous.

In plants having a bunch-type growth habit, new stems are produced by tillering. A tiller is a stem that arises from a bud in the crown and grows vertically, remaining enclosed by the leaf sheath. Although all grasses produce tillers, only those that spread by tillering alone are referred to as bunch-type grasses. In plants with the rhizomatous growth habit, lateral growth occurs by horizontal creeping underground stems called rhizomes. Rhizomes are produced from buds in the crown that break through the outer leaf sheath. Rhizomes produce nodes that can give rise to new tillers. In plants having the stoloniferous growth habit, lateral growth occurs by horizontal creeping aboveground stems called stolons. Stolons are produced from buds in the crown that break through the outer leaf sheath. Stolons produce nodes that can give rise to new tillers. Stolons are usually green, whereas rhizomes are usually white. Vegetative structures of grasses Several vegetative features can be used to identify grass weeds. The most important are leaf blade characteristics and the structures associated with the collar. Vernation is a term used to describe the arrangement of the youngest leaf in the bud shoot.

Grasses with folded vernation have leaves that are folded in a V-shape. Leaves with rolled vernation are round with no folds. To determine if the grass has folded or rolled vernation, hold the plant between your thumb and index finger and roll it. If it rolls like a straw, it has rolled vernation, if it lies flat and has edges, it is folded. You can also determine vernation by cutting a cross-section of the stem just below the leaf blade. Leaf blades of grasses can vary in width and hairiness. Some grasses have leaf blades that are dominated by a single prominent vein in the center of the leaf. Others have equal-sized veins running lengthwise over the entire width of the blade. Leaf blade tips may terminate in a sharp point, a blunt tip, or keeled shape (boat-shaped tip). The collar region is located between the leaf blade and leaf sheath. It may or may not contain structures called ligules and auricles. A ligule is the membranous or hairy tissue located at the junction of the leaf blade and leaf sheath. Ligules can vary considerably in size and shape and may be membranous, a fringe of hairs, or absent.

Auricles are appendages that are considered an extension of the collar. They can be long or clawlike, small or rudimentary, or absent. Grass seedheads Seedheads may be useful in distinguishing among grass weeds. They can appear as open-panicle types, compact spikes, and divided spikes. Norton Brown Herbarium Part 7: Leaf Pubescence and Other Characteristics Introduction Leaves are usually the most recognizable parts of a plant and can be useful for plant identification. Unique combinations of shape , color, tips, bases, or hairs make leaves great indicators of plant identities. Simply recognizing if the position of leaves on the stem is opposite or alternate to each other can greatly narrow down the number of possibilities for the identity of a particular plant. Other useful features are whether the leaf is simple or compound (made up of several parts), or if it is deciduous (falls off in autumn) vs. evergreen. Because there are so many features to consider, the terminology can become a bit overwhelming. In this guide, we will present discriptions and visuals of many of the terms you will see in the interactive key . return Part 1: A Leaf Defined A leaf is basically the power generator of a plant.

Leaves have specialized cells that carry out photosynthesis when exposed to sunlight. In photosynthesis sunlight, water supplied by the roots, and carbon dioxide from the air produce oxygen and sugars (stored plant food). Although there are several types of leaves , a typical leaf has a blade (broad, flattened portion) and a stalk called the petiole. A leaf without a petiole, where the blade is directly attached to the stem or the branch, is called sessile. Any part of the leaf can be pubescent (hairy), glabrous (hairless), or can have glands, which are structures that excrete oil or nectar (e.g., on leaf petioles of cherry trees). Each leaf is associated with a bud that sits at the base of the petiole where it is attached to the stem ( see Picture 11 ). At the base of the petiole, there may also be a stipule or what looks like a small leaf or two. A stipule will frequently shed early in the season or it may persist. Some stipules extend around the entire stem, leaving a scar that encircles the axis when the stipule drops off, such as in Magnolias.

The visible lines running through the leaf blade are veins that carry the water and nutrients involved in photosynthesis to and from the rest of the plant. The network of veins includes a midvein (aka midrib) that runs through the center of the leaf. Secondary veins branch off from the midrib and tertiary veins branch off the secondaries. The patterns formed by the veins are called the leaf venation. If the veins branch from along the midvein, as in Picture 1, then the leaf has pinnate venation. If the veins originate from one point at the base of the blade, as seen in Picture 4, the leaf has palmate venation. The edge of the blade is called the leaf margin. Here, you may find teeth, or serrations, that can be useful in plant identification. Terms for different types of leaf margins can also be found here . leaf blade return Part 2: Leaf Type After defining the plant habit (is it a tree? a shrub? a vine?), classifying the leaf type is among the easiest and most important steps in identifying a plant. Broad-Leaved plants are the most common plants in the Mid-Atlantic region.

These are plants with wide leaf blades exposing a large surface area to the sun for photosynthesis and examples include the oaks, maples, and dogwoods. Alternatively, firs, pines and spruces, have needle-like photosynthetic organs. Scale-like leaves of junipers or cedars are comparatively short, overlapping, and resemble the scales of a fish. Picture 2: Types of leaves Most Broad-Leaved trees and shrubs in the Mid-Atlantic region are deciduous, that is, they shed their leaves in the fall every year and remain dormant throughout the winter. However, there are a few Broad-Leaved trees that are evergreen, which means that they keep at least some leaves throughout the entire year. Picture 3: Leathery Magnolia leaves Southern magnolia trees and rhododendron shrubs have broad leaves that are thick and leathery and can survive the cold and dry winters in this region. Most needle-like and scale-like leaves are evergreen. Exceptions are the needle-like but deciduous leaves of the American and Eurasian larches that turn a bright yellow before shedding in the fall. Part 3: Leaf Type: Simple and Compound Picture 4: A simple leaf.

Broad-leaved plants can be simple or compound. Oaks and most maples are examples of trees with a simple leaf where a single, undivided blade is attached to the stem by a petiole (leaf stalk). There is a bud (next year's growth) in the leaf axil at base of the petiole where it connects to the stem. The axil is the petiole/stem juncture that forms an angle, while the entire juncture is the node. If a leaf is divided into distinct smaller parts (called leaflets), it is a compound leaf. The stalk of a leaflet is called petiolule, not to be confused with the petiole, which is the stalk of the entire leaf. You will never find a bud where the petiolule (leaflet) connects, but only at the node where the petiole meets the stem ( see Picture 11 ). There are several types of compound leaves. Palmately compound leaves are made up of leaflets that are all attached at the same point where the petiole meets the blade. A blade composed of 5 leaflets Picture 5: A palmately compound leaf.

Pinnately compound leaves are also composed of leaflets, but these are connected to a main axis called a rachis (looks like the continuation of the petiole). If there is a single terminal leaflet on the rachis, the leaf is odd-pinnately compound. When there is a pair of leaflets at the tip of the rachis the leaf is even-pinnately compound (i.e., the leaf is composed of an even number of leaflets). If the leaf is twice compound because the rachis branches, it is bipinnately compound. If the leaf is three times compound, then it is tripinnately compound. A blade divided into 3 leaflets is trifoliate. A good trifoliate leaf to know in the Mid-Atlantic region is poison ivy (“leaves of three, leave it be”). Picture 6: A once odd pinnately compound leaf. Picture 9: Tripinnately compound leaf. Picture 10: A trifoliate leaf. A note of caution: It may be difficult at first to tell a leaf from a leaflet, that is, if a leaf is simple or compound.

If there is a petiole leading to an undivided leaf blade, then you have a simple leaf, but if there are leaflets it is a compound leaf. As mentioned before, the simplest way is to look for a bud in the axil of the leaf (where the petiole joins the axis). A leaf will have a bud (called a lateral or axillary bud) in this location; a leaflet will not (see picture 11 and Appendix III: Stems and Twigs ). The leaflet-stalk (petiolule) is attached to the rachis that bears all of the leaflets and is connected to the petiole. Picture 11: A single ash leaf that is pinnately compound. To know if a leaf is compound or simple, look at the location of the bud. A bud only occurs at the base of the leaf and there are no buds at the bases of leaflets. The rachis is the axis that connects the leaflets. return Leaf Arrangement There are different terms for the ways that leaves are arranged along the axis of the stem (not to be confused with the rachis of a compound leaf).

Most woody plants have an alternate leaf arrangement where there is only one leaf at each node. Here the alternately arranged leaves either spiral down the stem with minimal overlap, allowing for the most surface area to be exposed to sunlight, or they do not spiral and are arranged in one plane (distichous). Where leaves have an opposite arrangement, pairs of leaves are borne opposite each other at the same node. There are fewer woody plants with opposite rather than alternate leaf arrangement. There is a popular mnemonic device for remembering trees and shrubs of some families with oppositely arranged leaves, which is MADCAP Horse. While it does not cover all of the woody plants with opposite leaves, it is a helpful general rule for some groups. MADCAP Horse stands for: M – Maple Cap – members of the family Caprifoliaceae, such as honeysuckle and former members of this family, the viburnums (now in Adoxaceae) Horse – Horsechestnut When the pairs of opposite leaves are arranged along the stem perpendicular with respect to the next leaf pair, again for maximum exposure to sunlight, this is called decussate. Leaves that are almost, but not quite, opposite are termed subopposite.

If there are three or more leaves at the same node, then the leaf arrangement is whorled. return Part 5: Leaf Shapes Some common leaf shapes are round, egg-shaped (ovate), triangular (deltoid), or heart-shaped (cordate). It is important to note that within species and even individual plants you may see more than one typical leaf shape, and most plants will have several possible leaf shapes. This depends on environmental factors (light, soil conditions, water availability) or genetic variability. We present the most common leaf shapes below and in the interactive key . The shapes are generally determined by the location of the widest part of the leaf, as indicated by the lines in the pictures below. The prefix "ob-" signals the reverse of the indicated shape. For example, an ovate leaf has the widest part of the leaf at the base and an obovate leaf differs in that the widest part of the leaf is toward the tip. Picture 15: Ovate (egg-like) leaf shape. The base is the widest part of the leaf and the tip is narrower but rounded. Picture 16: Lanceolate leaf.

The widest part of this leaf shape is at the middle while both ends are tapered (the tip more acutely so). Picture 17: Obovate leaf. The widest part of the leaf is towards the tip Picture 18: A cordate leaf. Heart-shaped, where the base is notched and with a tapering tip. Picture 19: Elliptical leaf shape. An oval leaf where the middle is the widest part and both ends taper evenly. return Part 6: Leaf Tips, Bases and Margins Besides basic shape, leaves have a number of other physical characteristics that are useful for identification. For example, the tips of leaves may be rounded, notched, or long and tapering. Picture 20 shows the leaf tips you will encounter in the key. The most common are acute (sharp angle), acuminate (coming to a long point), and obtuse (rounded). Leaf bases are shown in Picture 21. Picture 20: Leaf tips. Picture 20: Leaf bases. The margins of leaves (edges) may be toothed or without teeth (entire). There are many technical terms describing types of teeth.

A leaf margin is serrate if the teeth point forward towards the tip or dentate if the teeth point outwards. A margin with small serrations is serrulate and one with a tooth within a tooth is doubly serrate. If a leaf margin has rounded teeth, then it is crenate. Here are some common leaf margins. Picture 23: Features of an oak leaf. Several species of oaks and maples have unique and easily identifiable leaf shapes, because of the placement of projections called lobes and indentations that are called sinuses (Picture 23). A leaf can sometimes be identified by the number of lobes and unique structures found on the lobe. For example, some species of oaks have sharp-pointed lobes that are tipped by a bristle (the red oak group), such as the leaf in Picture 23. Other species of oaks have rounded lobes and lack a bristle at the tip (the white oak group). return Part 7: Leaf Pubescence Any part of a leaf can be pubescent (hairy), but more often the underside of the blade is pubescent rather than the upper surface.

The texture, cell-type, color and location of hairs can be important characteristics for plant identification. There are as many technical terms for hairs as there are botanists in the world, and it is often best to describe the hair type in detail rather than resort to a term that may have different meanings from author to author. Leaves that are not pubescent are glabrous, or hairless. Occasionally, leaves (as well as stems and fruit) may have a whitish bloom (glaucous) that easily rubs off. This is a waxy layer and in some species of bayberries the bluish bloom can be wiped to green (see Picture 24). Midrib - definition of midrib by The Free Dictionary Midrib - definition of midrib by The Free Dictionary Also found in: Thesaurus , Encyclopedia , Wikipedia . mid·rib The central or principal vein of a leaf. midrib (Botany) the main vein of a leaf, running down the centre of the blade mid•rib the central or middle rib of a leaf. [1690–1700] The central or main vein of a leaf. See more at leaf .

ThesaurusAntonymsRelated WordsSynonymsLegend: midvein nervure , vein - any of the vascular bundles or ribs that form the branching framework of conducting and supporting tissues in a leaf or other plant organ Want to thank TFD for its existence? Tell a friend about us , add a link to this page, or visit the webmaster's page for free fun content . Link to this page: Mapping boron deficiency risk in soils of south-west Western Australia using a weight of evidence model Adaxial matte surface to subnitid, glabrous or slightly hirtellous on midrib, abaxial surface with the midrib, and sometimes lateral veins as well, most of which are slightly are puberulent or hirtellous and also with coarse, subapressed hairs, very densely tomentose, petiole 0.

Glossary Acorn—hard-shelled nut with pointed tip; found on oak trees Alternate—arranged singly along a twig, branch, or shoot Angled—with distinct ridges; not smoothly rounded Aroma/Aromatic—producing a scent; fragrant Axis (plural: axes)—central stalk of compound leaf or flower cluster B Bark—outer covering of trunk and branches Bipinnate(ly)—leaflets arranged on side branches off of the main axis Blade—broad and expanded part of the leaf Blighted—affected by a blight, a bacterium, fungus, or virus that impairs growth Bract—modified leaf structure that usually appears at the base of a flower (or their clusters) or a fruit (or fruits) Branchlet—youngest and smallest part of a branch Bristle tip—stiff hair at leaf tip Bud—young (not developed) leaf, flower, or shoot frequently covered with scales Bundle scar—small dots or lines found within the leaf scar when leafstalk is broken Bur—prickly covering of seeds or fruit C Calyx—sepals of a flower Cap—hardened, scaly top covering of an acorn Capsule—dry fruit with 2 or more seeds Catkin—small, un

isexual flower or fruit cluster that is typically drooping and caterpillar shaped Chambered (pith)—divided crosswise by plates Cluster—bundled similar elements Coarse-toothed—leaf edge with large teeth Compound—leaf made up of 3 or more smaller leaflets Cone—fruit with overlapping scales around an axis Continuous (pith)—twig center not chambered or hollow Cross-hatched—with sets of intersecting, parallel lines Crown—the combination of branches, twigs, and leaves at the top of a tree that refers to a tree’s overall shape Cultivated—planted and preserved by humans D Deciduous—losing foliage at the end of the growing season Distribution—geographic range Double-toothed—each tooth having smaller teeth Dutch Elm Disease—disease caused by fungus, Ophiostoma ulm Girdle(d)—to remove a band of bark from a tree in order to kill it Gland—small knob on a leaf’s surface that secretes a substance H Hayfever—allergic condition; symptoms frequently include sneezing, watery and itching eyes, and runny nose Husk—shell or outer covering of some fruits and seeds Hybrid—offspring that results in the cross of two different species L Lateral

 vein—vein that runs parallel to the natural curve of the leaf Leaflet—leaflike subdivision of a compound leaf Leaf base (or base)—lower portion of the leaf towards the leafstalk Leaf scar—mark remaining on the twig or branch when a leaf falls or is removed Leafstalk—stem that supports the leaf and connects it to the branches; also called petiole Lenticel—corky, circular or stripelike spot on bark; pore for breathing Lobe—leaf edge divided into separate, often rounded sections Lowlands —areas that are low in elevation compared the surrounding areas M Maple sugar—sugar made from concentrated sap from Sugar Maple tree Midvein—central vein of a leaf; also called midrib N Oblong—elongated in form with parallel sides Obovate—oval shape with broad tip Opposite—arranged in opposing pairs along a twig Ornamentation—decoration Ovate—oval shape with broad base P Palmate(ly)—major veins spreading out to the edges from one point at the base of the leaf Petal—brightly colored flower part; one of a group, often found in a circle Petiole—Stalk that supports a leaf; leafstalk Pinnate(ly)—

with leaflet arrangement in 2 rows along main axis Pith—spongy center tissue of a twig or stem Pod—fairly dry, flat fruit containing one to many seeds Pulp—part of fruit that is moist and soft R Resin—frequently aromatic plant secretion Resin-dot—small, circular, yellow spots S Samara—dry, 1-seeded fruit with a wing; key Sap—fluid that circulates through a tree Saw-toothed—leaf edges that are divided into short, sharp-pointed protrusions Scale—thin covering of a bud or acorn Scaleless—without scales Seed—part of mature fruit that house the embryo Seed bed—area for growth Sepal—part of flower that surrounds the reproductive organs; often green Shoot—young twig or stem that is growing Shrub—typically small plant with several stems growing from base; without single trunk Side bud—bud in lateral position (on side of twig, not terminal or end bud) Simple—made up of only one blade Sinus—space between two leaf lobes Species—group of individuals with small variation who interbreed Spine—small, short woody growth emerging from twig or stem; a thorn Sprout/Shoot—young plant growth Spur

 branch—short side branch with dense, crowded leaves Stalkless—without a leafstalk Stamen—a male flower structure Stipule—leaflike scale found at leafstalk base; frequently paired Striation—parallel line

Question: What is the vein running along the centre of a leaf called?
Answer: Midrib