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A really extraordinary botanical glossary can be found at A glossary of botanical terms. Bluntly, it is far better than our own glossary, but lacks images and hyperlinks. I can't seem to get the French version to work, but it may be even better.
Actinostele: a type of
protostele
that looks like a star in cross section. The walls of the stele are
heavily reinforced with lignin and are relatively thick.
Xylem
occupies the center but the phloem occupies the indentations in the xylem. This
generates the star-like pattern. Image from the Botany
210 site of Prof. David Webb at the University of Hawaii at Manoa.
Active transport: transport across a cell membrane which requires energy generated by the hydrolysis of some energy carrier (usually ATP). The selective active transport of ions (usually sodium) out of the cell is often used as a secondary energy storage mechanism. See ion gradient system.
Alternation of generations: a life cycle in which there are two stages: (a) a diploid, sporophyte stage which produces haploid spores by meiosis, and (b) a haploid, gametophyte stage which produces haploid gametes of two types, usually called male and female but technically microgametes and megagametes. The female gamete is fertilized to become a diploid zygote, which matures to become a diploid sporophyte, completing the cycle. Either the gametophyte or the sporophyte stage may be, and typically is, very small and remains attached to the other stage.
Amphithecium: The outer, "ectodermal" cell layer of the sporophyte in basal plants.
Annual: a plant with a lifespan of one year.
Annulus: specialized
structure of some fern sporangia that is involved in the opening of the
sporangium. In some mosses, on drying out the cells of the
annulus contract and the sporangium ruptures, releasing the spores.
In others, the annulus bears the peristome
teeth, which perform a similar function. Image
from the Biology 3560 site
of the University of Lethbridge (Alberta).
Anther: in a flower, the terminal part of the stamen which holds the pollen; an antheridium.
Antheridium: reproductive structure that produces male gametophytes (pollen).
Apical meristem: see meristem.
Apomorphy: a character state which is unique to a single, terminal taxon. Example: among primates, complex grammar is an apomorphy of human beings. It is quite diagnostic of humans, but useless in determining phylogenetic relationships because it is not a shared, derived characteristic, or synapomorphy, of any larger group.
Arborescent: of tree-like growth-habit, a tree. A woody plant.
Archegonia: reproductive structure that
produces female gametes (egg). Image from the Department
of Botany site of the University of Wisconsin at Madison.
Arthrodontous: of moss sporophytes, having peristome teeth which are formed by walls growing between the rows of cells making up the mouth of the spore capsule. See Tree of Life: Bryopsida.
Autotroph: an organism which obtains energy from inorganic sources, sunlight or the oxidation of inorganic chemicals.
Autotrophic nutrition: synthesis of organic food molecules from inorganic compounds such as carbon dioxide
Axis: another word for stem.
Biennial: a plant with a lifespan of two years. Often only flowers and goes to seed (yes, that's the source of this phrase) during the second year.
Bisaccate: a
pollen grain with two sacci.
The two "sacs" or bladders are used to promote wind dispersal.
Pollen of this type is known from as early as the Devonian. Image from the Earth
History Research Center.
Budding: reproduction by binary fission, a characteristic form of propagation in yeasts. "The onset of the cellular events is accompanied by the nuclear events of mitosis. ... The initial events of budding can be seen as the development of a ring of chitin around the point where the bud is about to appear. This reinforces and stabilizes the cell wall. Enzymatic activity and turgor pressure the act to weaken and extrude the cell wall. New cell wall material is incorporated during this phase. Cell contents are forced into the progeny cell, and as the final phase of mitosis ends a cell plate, the point at which a new cell wall will grow inwards from, forms." Reproduction in the fungi (former http:// www-micro. msb. le. ac. uk/ 224/ mycology/ 2. html).
Bulb: an underground stem bearing modified (scalelike) leaves and fibrous basal roots; generally food storage organs.
Bulbil: a bulb produced above the ground, often on the flowering stem or on a leaf axil.
Calyptra:
in mosses, a derivative of the distal archegonium
forms a hard, protective layer around the developing sporophyte called the epigonium.
Later the epigonium breaks up, but the sporophyte retains a conical "dunce cap" over its distal
end, and sometimes a ring around the base. The cap is the calyptra.
The piece retained around
the base is the vaginula.
Cambium: a layer of actively dividing cells (lateral meristem), found within stems and roots, that gives rise to secondary growth in perennial plants, causing an increase in girth. There are two main types of cambium: vascular cambium, which gives rise to secondary xylem and phloem tissues, and cork cambium (or phellogen), which gives rise to secondary cortex and cork tissues, as in bark. Image from the Population Biology site of San Diego State University. The vascular cambium surrounds the roots, trunk, branches, and shoots, extending throughout a tree. Each year, the vascular cambium produces a new layer of phloem toward the outside of the tree and a new layer of xylem, or wood, toward the inside.
Carpel: the female reproductive organ of a flower, consisting of stigma, style and ovary.
Cauloneme: a lateral process from the protoneme (initial, threadlike process) which develops into the gemetophore in mosses.
Cellulose: polysaccharide that consists of a long unbranched chain of glucose units; cellulose is the main constituent of the cell walls of most land plants.
Chitin:
a polymer of repeating sugar molecules (a slightly modified glucose,
poly-N-acetyl-D-glucosamine). See image. Chitin is the material which makes up the
exoskeleton of insects and, in more or less modified form, in almost all arthropods. In arthropods, chitin occurs in a cross-linked form, α-chitin.
Significantly, it is also found in the radular "teeth" of mollusks,
the setae (bristles) and jaws of annelid worms, and the cell walls of Fungi. So,
this is exceedingly ancient stuff, possibly predating the split between bacteria
and metazoans. [What may be of sociological interest is that the 1,5
aldose linkage was missing from the middle glucose in this diagram and no one
spotted it for over a year ....]
Clade: a group of organisms consisting of an organism and all of its descendants.
Climber: a soft- or non-woody-stemmed vine that clasps the stems or branches of trees and shrubs to raise its foliage and flowers above the ground; a type of growth form.
Columella:
this is another one of those anatomical terms of almost unbelievable
generality. It refers to any small rod-like structure (and some that are
not rod-like in the slightest), such as the ear ossicle of reptiles, the basal
column of univalves in gastropods, the sterile support of the fruiting body in
fungi, and, for our purposes, either (a) a structure closely analogous to the
fungal columella in the sporophyte of basal plants; or (b) the central portion
of the root cap in higher plants.
Complex tissue: tissue that consists of more than one cell type, e.g. phloem.
Cork a plant tissue composed of cells whose walls are impregnated with suberin and are non-living at maturity; cork is produced by the cork cambium.
Cork cambium: a narrow cylindrical sheath of meristematic cells that produces cork cells to replace the epidermis during secondary growth (growth in width). A type of cambium, also called phellogen.
Cortex: a primary tissue composed mainly of parenchyma cells, which extends between the epidermis and the vascular tissue.
Costa: the midline vein, nerve or midrib of a bryophyte leaf (or phyllid).
Cotyledon: the embryo leaf or leaves of seed
plants that absorbs nutrients packaged in the seed, until the seedling is able
to produce its first true leaves and begin photosynthesis. "The
number of cotyledons present in an embryo is an important character in the
classification of flowering plants (angiosperms). Monocotyledons (such as
grasses, palms, and lilies) have a single cotyledon, whereas dicotyledons (the
majority of plant species) have two. In seeds that also contain endosperm
(nutritive tissue), the cotyledons are thin, but where they are the primary
food-storing tissue, as in peas and beans, they may be quite large. After
germination the cotyledons either remain below ground (hypogeal) or, more
commonly, spread out above soil level (epigeal) and become the first green
leaves. In gymnosperms there may be up to a dozen cotyledons within each
seed." Tiscali.
Image from the Online
Biology Book by Dr. Mike Farabee of Estrella Mountain Community College.
Crista: (pl. cristae) (1) of mitochondria, folds in the internal membrane of the mitochondrion which gives the organelle its characteristic appearance. This is the site of the electron transport chain in oxidative metabolism. The cristae, therefore, serve as the physical link between the tricarboxylic acid cycle and oxidative phosphorylation (ATP synthesis). See also Mitochondrion - Wikipedia. (2) more generally, a crest (its literal meaning in Latin) or ridge.
Crozier: the spirally coiled "fiddlehead" of an immature fern leaf.
Cupule: structures that surround one or more ovules or seeds, e.g., the "cap" of an acorn. The cupule lobes may be free or united.
Cuticle: an impermeable layer of cutin on the outer walls of epidermal cells.
Cutin: the waxy substance
of which a cuticle is composed. The basic structure of cutin is shown in
the image.
checked ATW050802