### definite unit | natural plant organ | reproductive structure:

Gemma
* are tiny, lens-shaped pieces of tissue that become detached from the thallus.
* e are asexual propagules that are formed in gemmae cups and splashed out by the rain
  - frequently wine red to dark brick red
  - germinate directly into new gametophytes
* give rise to an indi- vidual identical with the parent.

### definite unit | natural plant organ | reproductive structure:

Seed coat
* Most seed coats have inner layers
  - membranous layers
  - provide protection
* Some seed coats are particularly durable and their seeds can survive in the seed bank for years.
* are source of protein, used in bread or health foods.
* can be thin and soft as in beans or thick and hard as in locust or coconut seeds
  - carry anthracnose spores without any visible symptoms
* contain the alkaloid harmine and are especially toxic when ingested.
* help protect the embryo from injury and also from drying out.
* prevent drying out and the cotyledons provide nutrients for the growing embryo.

Sorus
* SORI are compact, and borne on the lower surface of leaves
  - short-stalked, and borne on the lower of the two leaf lobes
* Sori are clusters of sporangia on the stems and leaves
  - sporangia, where spores are produced by meiosis
  - come in all shapes, sizes and locations
  - contain sporangia where reproductive cells undergo meiosis and where spores are produced

Sporocarp
* are most dramatic in producing numerous infective hyphae
  - soft and green when they first start to develop, but then turn hard and brown
* usually contain more than one spore, and in some cases, many thousands of spores.

Root cap
* Some root caps are part of carrots
  - roots
  - sangs
  - taproots
* contain especially sensitive cells.

### definite unit | natural plant organ:

Root hair
* Some root hair is part of carrots
* absorb water and elements dissolved in it.
* absorbs water and mineral salts from the soil.
* allow for the absorption of water and nutrients from the soil.
* appear in the region where elongation has ceased.
* are a type of rhizoid
  - always in close contact with soil particles
* are epidermal cell extensions that increase absorptive surface area
  - extensions which increase surface area, thus enhancing uptake
  - especially important for water uptake from soil
  - important to plants because they increase the strength of the roots
  - like all cell walls and have a primary cell wall
  - most important to a plant because they a. anchor a plant into the soil
  - present on nodal roots
  - responsible for most of the water and mineral uptake
  - sensitive to the oxygen in solution
  - specialized cell extensions which penetrate into the openings between soil particles
  - the smallest type of roots complete with a functional stele
  - thin-walled extensions of the epidermal cells in roots
  - tube-like extensions that absorb nutrients and water
  - turgid as a result of their greater solute potential
  - visible even on the radicle root of a young seedling
* arise from some of the epidermal cells.
* can be sites for extensive mucilage production.
* detect gravity so the root grows downward.
* develop in a zone a short distance behind the root cap
  - just behind the growing tip of the root
  - on the meristematic region of the root
* extend from all of the dandelion roots.
* form an important surface over which plants absorb most of their water and nutrients.
* have a large surface area and absorb water and minerals for the plant.
* increase surface area for water and mineral absorption.
* increase the absorbing surface of the root
  - root's surface area and absorptive capacity
  - surface area many times over
* is part of roots
  - the entire time single celled
* produce as a rule carbohydrate-containing mucigel.
* provide huge surface area for absorption.