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gametophyte |
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PLANT |
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The main, ultimate, gamete-bearing stage in the haploid (n chromosomes) phase of a taxon's life cycle. Two morphologically and genetically distinct and alternate stages together constitute the complete life cycle in sexually reproducing taxa, the other phase (sporophytic) being diploid (2n chromosomes). Any taxon whose life cycle is confined to one or the other phase is limited to asexual means of reproduction, since sexual reproduction and consequent genetic recombination are impossible without alternation between haploid and diploid states via meiosis and fertilization. The term gametophytic applies to any part of the haploid phase, including all unicellular to multicellular entities belonging to it, whereas gametophyte is reserved for the principal and directly gamete-producing stage of that phase. In all vascular plant taxa the sporophyte is the dominant and most conspicuous phase of the life cycle. The gametophytes of "lower" vascular plants (ferns and "fern-allies") are physically independent of the sporophytes and, though inconspicuous, merit description in their own rights. Those of gymnosperms and angiosperms are minute and physically dependent upon (contained within) sporophytic structures and are not usually included in morphological descriptions. In the flowering plants at least, the haploid phase is (presumably evolutionarily) reduced to such a degree that the existence of gametophytes per se is debatable. |
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squamella 3 pl. squamellae |
= lodicule, squamule |
STRUCTURE |
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One of two or three small, scale-like structures inserted at the base of the androecium, distal to the palea, in most grass (Poaceae) flowers; often regarded as a vestigial branch or perianth member. |
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hexa… |
= six-… |
prefix |
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Indicating presence of or constitution by six entities of the type denoted by the term's stem; as in hexandrous, hexacarpellate, hexacolporate. |
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superaxillary |
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insertion |
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Internodal but close to and directly above the axil(s). |
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jacket cell |
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STRUCTURE |
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Any of the cells forming the portion of an antheridial wall between the basal cells and the cap cell(s). |
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tree-like |
= dendritic |
architecture |
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Like the branched axial structure of a tree. |
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alternate 1 |
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arrangement |
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Inserted singly along the axis, each at a different level and each diverging on a different radius than the ones next above and below. |
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auricle |
= ear |
STRUCTURE |
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A small, rounded, lateral lobe at the base of a laminar structure, lying in more or less the same plane as the remainder of the lamina. |
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megagametophyte |
> embryo sac |
PLANT |
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A gametophyte whose fertile organs (gametangia) are all archegonia. |
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obovoid |
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solid shape |
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Inversely ovoid (egg-shaped). |
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claw |
= unguis |
STRUCTURE |
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The abruptly much narrower proximal portion, when present, of a laminar structure, esp. a petal; of variable shape itself, but usually attenuate toward the base. |
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crenulate |
= small-scalloped |
margin |
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Finely crenate (scalloped). See also dentate (toothed), denticulate (small-toothed), serrate (sawtoothed), serrulate (small-sawtoothed). |
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primary vein |
> costa, midnerve (not recommended), midrib, midvein, rib; >< lateral vein |
STRUCTURE |
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A strand belonging to the first order of vasculature in a leaf or other basically laminar structure. See also secondary vein, tertiary vein, veinlet. |
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disk |
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STRUCTURE |
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See disc. |
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reticulate 3 |
= netted |
relief |
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Having prominulous, more or less regularly interconnected lines. |
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seed leaf |
= cotyledon |
STRUCTURE |
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Any of the one or more primary foliar structures of an embryonic seed plant, proximal to all succeeding leaf primordia; sometimes serving as a storage organ for food reserves in the seed, as in peas and beans. |
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fragrant |
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odor |
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Sweet or otherwise pleasant. |
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spinose 3 |
= aculeate, spiny |
margin |
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Having slender, stiff, sharp projections oriented in the general plane of the structure. See also spinulose. |
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headless 1 |
= acephalous |
architecture |
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Not terminated or surmounted by a head-like structure, esp. when one might be expected. |
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intercostal |
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insertion |
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Between the costae. |
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…valleculate |
= …colpate, …fossulate, …furrowed, …grooved, …sulcate |
architecture |
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Having the number of valleculae indicated by the prefix; esp. fruits of Apiaceae (Umbelliferae); as in tetravalleculate, 8-valleculate. |
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aculeate |
= spinose, spiny |
margin |
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Having slender, stiff, sharp projections oriented in the general plane of the structure. |
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aril 1 (broad sense) |
> arillode, arillus |
STRUCTURE |
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An appendicular structure that wholly or partly envelops a seed and is produced from or a modification of the funicle, raphe, outer integument, or (in some Pinophyta) a subtending involucre; usually fleshy or pulpy, sometimes spongy or tufted-capillate, often brightly colored. |
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macrospore (not recommended) |
= megaspore |
STRUCTURE |
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A female spore; a spore of the larger of two types produced by the sporophytes of a heterosporous taxon; produced in a megasporangium; giving rise upon germination to a megagametophyte. |
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bractlet 1 |
= bracteole; < bract |
STRUCTURE |
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A diminutive bract, or a bract that is smaller than others present. |
