deciduous: falling seasonally, e.g. of the leaves or bark of some trees. cf. evergreen.
declinate: angled downwards or forwards. cf. decurved.
decompound: more than once compound.
decumbent: spreading horizontally but then growing upwards.
decurrent: extending downwards beyond the point of insertion, e.g. of a leaf lamina extending downwards to form a flange along the petiole.
decurved: angled downwards and curved or curled. cf. declinate.
decussate: in opposite pairs, with successive pairs borne at right angles to each other.
definite: of a constant number; of stamens, twice as many as the petals or sepals, or less; of an inflorescence, ending in a flower or an aborted floral bud.
deflexed: bent abruptly downwards. cf. inflexed.
dehiscent: breaking open at maturity to release the contents.
deltoid (= deltate): triangular with the sides of about equal length.
dendritic: of a trichome, with branches arising along the main axis, i.e. tree-like.
dendroid: tree-like in form but not in size. cf. arborescent.
denticle: a small tooth; in Coprosma (Rubiaceae), thick papillate tubercles on the margin of the interpetiolar stipules.
denticulate: finely toothed.
depressed: flattened as if pressed down from the top or end.
determinate: of growth or branching, with a bud or flower terminating the growth of the main axis; of an inflorescence, see definite.
dextrorse: turned towards the right. cf. sinistrorse.
diadelphous: having the stamens united into two groups, or all but one united in a group and one free. cf. monadelphous.
diaphanous: extremely thin and transparent.
dichasium: a cymose inflorescence with opposite branching below the flower which terminates each axis. cf. monochasium.
dichlamydeous: of a flower, having two whorls of perianth parts. cf. monochlamydeous.
dichotomous: forking into two equal branches resulting from division of the growing point.
diclinous: having the stamens and the carpels in separate flowers. cf. monoclinous.
dicotyledon: a flowering plant whose embryo has two (rarely more) cotyledons (seed leaves). cf. monocotyledon.
didymous: borne in pairs; of anthers, having two lobes, with scarcely any tissue connecting them.
didynamous: of an androecium, consisting of four stamens, two being distinctly longer than the other two. cf. tetradynamous.
digitate: branching from the axis or stalk like the fingers of a hand.
dimidiate: appearing to be halved, as when half an organ is so much smaller than the other that it seems absent.
dimorphic: of two different forms.
dioecious: having the male and female reproductive structures on separate plants. cf. monoecious.
diplecolobous: of cotyledons in a seed, twice folded transversely.
diploid: having two of the basic sets of chromosomes in the nucleus. cf. haploid, polyploid.
disc: a plate or rim of tissue, derived from the receptacle of a flower, occurring between whorls of floral parts.
disc floret: an actinomorphic flower in Asteraceae. cf. ray floret.
discolorous: of different colours; of leaves, having the two surfaces different in colour; variegated. cf. concolorous.
dissepiment: a partition (septum) within an ovary or fruit, derived by fusion of adjacent carpels.
distal: remote from the point of origin or attachment. cf. proximal.
distichous: arranged in two rows on opposite sides of a stem and thus in the same plane.
diurnal: of flowers, opening only during daylight hours.
divaricate: widely spreading.
division: the major taxonomic rank within the Plant Kingdom. Alternative name for phylum.
domatia: small structures on the lower surface of a leaf in some woody dicotyledons, located in the axils of the primary veins and usually consisting of depressions partly enclosed by leaf tissue or hairs. sing. domatium.
dorsal: of a lateral organ, (relating to the side) facing away from the axis, i.e. the 'back'; of a thallus, facing away from the substratum. cf. ventral.
dorsifixed: attached at or by the back.
dorsiventral: having structurally different upper and lower surfaces. cf. isobilateral.
drupe: a succulent fruit formed from one carpel, having the seed(s) enclosed in an inner stony layer of the fruit wall. adj. drupaceous (which is often used to mean drupe-like but not strictly a drupe). cf. berry, pyrene.
duplicate: folded twice.
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Last updated on 13 May 1999.