An acorn that has partial damage is classified as only having damage to the non-vital parts of the propagule. Therefore, when the acorn embryo is damaged the development of the seed is negatively affected. The affected development causes a difference in shoot and root biomass because the cotyledon is lost. The cotyledon is a necessity of plants and in this case becomes the leaves of the plant. In other cases it helps scientists determine which type of flowering plant it will later develop into. The cotyledons are also an essential source of energy for the development of the seed and plant.
There are two common types of soil that are used in scientific studies, nutrient rich soil and nutrient poor soil. The predation of the seeds is not as important as the nutrient level of the soil. Different plants over time have adapted to grow in these different conditions over time. The acorns of the cork oak tree have better regeneration and development in nutrient rich soil. The smaller cotyledon acorns that grow in nutrient rich soil develop.
Acorn
The acorn is the fruit of the oak tree. It is a nut, and contains a single seed (rarely two seeds), enclosed in a tough, leathery shell. Acorns vary from 1 – 6 cm long and 0.8 – 4 cm broad. Acorns take between about 6 or 24 months (depending on the species) to mature.
Acorns are one of the most important wildlife foods in areas where oaks grow. Creatures that make acorns an important part of their diet include birds, such as jays, pigeons, some ducks and several species of woodpeckers. Small mammals that feed on acorns include mice, squirrels and several other rodents. Such large mammals as pigs, bears, and deer also consume large amounts of acorns: they may constitute up to 25% of the diet of deer in the autumn. In some of the large oak forests in southwest Europe, traditionally called "dehesas", pigs are still turned loose in oak groves in the autumn, to fill and fatten themselves on acorns.
Acorns contain tannins, which are toxic to some animals such as horses. The tannins can be soaked out, using water.
President of Belarus
The president of the Republic of Belarus (, ) is the head of state of Belarus. The office was created in 1994. A president is chosen by other Belarusians every five years in a national vote. Alexander Lukashenko is the only person who has been president.
Jay
The jays are several species of medium-sized, usually colorful and noisy birds in the crow family Corvidae.
Clubmoss
Clubmosses are a group of plants in the Lycopodiophyta, which are the most ancient group of land plants. The clubmosses are an order Lycopodiales, (or a subclass Lycopodiopsida).
Clubmosses are thought to be structurally similar to the earliest vascular plants, with small, scale-like leaves, homosporous spores borne in sporangia at the bases of the leaves, branching stems (usually dichotomous), and generally simple form.
A powder known simply as "lycopodium", consisting of dried spores of the common clubmoss, was used in Victorian theater to produce flame-effects. A blown cloud of spores burned rapidly and brightly, but with little heat. It was considered safe by the standards of the time.
The group is now split into two families:
Horsetail
The horsetails are a class in the Pteridophyta (ferns). They were one of the most important plant groups in the Palaeozoic era. They are seen in the coal measures of the Carboniferous period, and some were trees reaching up 30 metres. The group is now almost extinct, but one genus survives. They are vascular plants that reproduce by spores and not by seeds. The name "horsetail" arose because the branched species somewhat resemble a horse's tail.
Equisetum is the only living genus of horsetails. The name "Equisetum" comes from the Latin ("equus" = horse; and "seta" = bristle). The genus includes 15 species.
Horsetails are native on all continents except Australasia and Antarctica. They are perennial plants, either herbaceous, they die back in winter (most temperate species) or they are evergreen (some tropical species, and the temperate species "Equisetum hyemale, E. scirpoides, E. variegatum" and "E. ramosissimum"). They mostly grow 0.2-1.5 m tall, though "E. telmateia" can exceptionally reach 2.5 m, and the tropical American species "E. giganteum" 5 m, and "E. myriochaetum" 8 m.
In these plants the leaves are very small, in whorls joined together to make sheaths around the stem. The stems are green and photosynthetic, also distinctive in being hollow, jointed and ridged, usually with 6-40 ridges. There may or may not be whorls of branches at the nodes; when present, these branches are identical to the main stem except smaller.
A superficially similar flowering plant ("Hippuris", "mare's tail", in the family Plantaginaceae), unrelated to the genus "Equisetum", is occasionally misidentified as a horsetail.
Green algae
Green algae are microscopic protists. One can find them in all sorts of natural water: salt water, freshwater and brackish water. The group is less used in classification today. Although most are descended from a common ancestor, some are not. Some of their descendants, the land plants are not included in the group, so the group is not monophyletic.
The green algae are the large group of algae from which the higher plants developed.
The green algae include unicellular and colonial flagellates, usually but not always with two flagella per cell, as well as various colonial, coccoid, and filamentous forms. In the Charales, the closest relatives of higher plants, full differentiation of tissues occurs. There are about 6000 species of green algae. Many species live most of their lives as single-cells, other species form colonies or long filaments.
Brackish water
Brackish water (less commonly brack water) is salt water and fresh water mixed together. It is saltier than fresh water, but not as salty as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers.
Some human activities can produce brackish water, mostly certain civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish pools for freshwater prawns.
Technically, brackish water contains between 0.5 and 30 grams of salt per litre—more often expressed as 0.5 to 30 parts per thousand (ppt or ‰). Thus, "brackish" covers a range of salinity regimes and is not considered a precisely defined condition. It is characteristic of many brackish surface waters that their salinity can vary considerably over space and/or time.
The term brackish water comes from the Low German word "Brack", which is a small lake made when a storm tide breaks a dike and floods land behind the dike.
The most important brackish water habitats are estuaries, where a river meets the sea, mixing salt and fresh water. The River Thames flowing through London is one of the most familiar of river estuaries.
Another important brackish water habitat is the mangrove swamp or mangal.
Some seas and lakes are brackish. The Baltic Sea is a brackish sea adjoining the North Sea.
The Caspian Sea is the world's largest lake and contains brackish water with a salinity about one-third that of normal seawater. The Caspian is famous for its peculiar animal fauna, including one of the few non-marine seals (the Caspian seal) and the great sturgeons, the source of caviar.
Brackish seas
Brackish water lakes
Coastal lagoons, marshes, and deltas
Estuaries
Flagellate
Flagellates are cells with one or more whip-like organelles called flagella. Some cells in animals may be flagellate, for instance the spermatozoa of most phyla. Flowering plants and fungi do not produce flagellate cells, but the closely related green algae and chytrids do. Many protists take the form of single-celled flagellates. They are found in most lines of eukaryotes, and it is likely that all surviving eukaryotes developed from them.
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