page_title: Glossary of botanical terms
section_title: D
hierarchical_section_title: Glossary of botanical terms / D
caption_attribution_description: The swellings are domatia housing myrmecophile ants which protect the tree. An eastern Africa species, also known as Swollen Thorn and placed in the Vachellia genus by some. Photo from Songea region, Tanzania.
context_page_description: This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary of leaf morphology.
context_section_description: deciduous
  Dehiscing and falling seasonally, as with bark, leaves, or petals. Contrast persistent.
  declinate
  Curving downwards, and then upwards at the tip. Often qualified, e.g. declinate-ascendant.
  decompound
  Divided to more than one level, e.g. in bipinnate leaves, in which the leaflets of what would otherwise be a pinnate leaf are themselves pinnately divided.
  decorticate
  1.  (intr. v.) To shed the outer bark of a tree, usually seasonally as part of the natural growth cycle.
  2.  (tr. v.) To strip the peel, crust, bark, or other surface tissues from a plant or from harvested material, such as in extracting fibre from harvested Agave leaves.
  decumbent
  Having branches growing horizontally along the ground but which are turned up at the ends.
  decurrent
  Extending downwards beyond the point of insertion, e.g. when the base of a leaf or a fungal gill is prolonged downwards along the stem in a raised line or narrow wing.
  decussant
  A synonym of decussate; the usage decussant is questionable and occurs rarely, probably as an error. The formally correct usage is decussate.
  decussate
  Opposite with successive pairs borne at right angles to the last; generally applied to the arrangement of leaves.
  definite
  Of a constant number, e.g. twice as many stamens as petals or sepals (or less), or an inflorescence ending in a flower or an aborted floral bud, typically a cymose inflorescence. Contrast indefinite.
  deflexed
  Bent downwards. Contrast inflexed.
  dehiscent
  Breaking open at maturity to release contents; refers e.g. to the opening of fruits to release seeds, of anthers to release pollen, and of sporangia to release spores. Contrast indehiscent.
  deltoid
  Shaped like the uppercase Greek letter Δ, i.e. like a more or less equilateral triangle.
  dendroid
  Tree-like; branching like a tree.
  dentate
  Toothed, especially in reference to leaf margins.
  denticulate
  Finely toothed; a diminutive form of dentate.
  deserticolous
  Inhabiting a desert.
  determinate
  Limited, usually in growth. Contrast indeterminate.
  diadelphous
  Referring to a class of adelphous structure in which the stamens or similar organs are connected in two adelphiae instead of just one.
  diaspore
  Any reproductive part of a plant adapted for dispersal and for establishing new plants; may be a disseminule such as a seed, or other parts such as specialised buds, branches, inflorescences, or fruits.
  dichasium
  A cymose inflorescence with all branches below the terminal flower in regular opposite pairs. Compare monochasium and pleiochasium.
  dichlamydeous
  Having a perianth which is divided into a separate calyx and corolla. Compare homochlamydeous.
  dichotomous
  Forking into two equal branches. This may result from an equal division of the growing tip, or may be sympodial, in which the growing tip is aborted and replaced. Typically refers to mode of branch growth, as in Aloidendron dichotomum, but also to other organs, such as the venation patterns on leaves, the thorns of various species of Carissa (which morphologically are branches), and the thalli or hyphae of various algae and fungi.
  dicotyledon
  A flowering plant whose embryo has two or more cotyledons (seed leaves). Contrast monocotyledon.
  digitate
  With segments spreading from a common centre, like the fingers of a hand. See also palmate and palmatisect.
  dimorphic
  Occurring in two different forms (with respect to shape and/or size), e.g. of stamens, fronds, or leaves. See also monomorphic (having a single form) and polymorphic (having many forms).
  dioecious
  (of vascular plants) Having male and female reproductive structures which develop only on different individuals and never on the same individual. Contrast monoecious.
  dioicous
  (of a bryophyte gametophyte) Having male and female reproductive structures which develop only on different individuals and never on the same individual. Contrast monoicous.
  diploid
  Having two complete sets of chromosomes in the nucleus of a sporophyte cell, i.e. one set from each of the parental gametes. This is often expressed symbolically as 2n, where n = the number of chromosomes in the haploid gamete.
  diplos
caption: Domatia at the bases of the thorns of Acacia drepanolobium, the "Whistling Thorn". Note the access holes.
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