GLOSSARY OF BOTANICAL AND TECHNICAL TERMS
Listing of specialist terms used within the Orchidopaedia.
The following is a list of terms given throughout the Orchidopaedia, and their meanings.
The letters given above will guide you to that part of the list to hasten your search. Use the Glossary link at the top of this page when coming to this window from any other, then select the required letter.
Alphabetical list.
A
Adnate - When an organ is fused with another type of organ (e.g. petals with sepals or sepals with the column)
Adventitious - Growing from an unusual part of the plant, like roots from midway along a stem, or new plants from along a stem instead of at the base, or on an inflorescence. These latter two are also known by the term Keiki.
Anther - The male part of the flower, in most orchids developed into 2 or more pollinia and associated structures involved in pollination and pollen transfer by the pollinator.
Apex - The outermost or highest point.
Apical - Of the Apex
Arboreal - Living in the trees.
Articulate - Having a point of flexion or a junction that is clearly evident to the observer.
Auriculate - Literally 'having ears' (auricles), used in reference to outgrowths of the anther in some orchids.
Axillary - Of the axil, the upper side of the point at which a leaf (or branch) joins a stem.
B
Basionym - The initial name given to a species, which may be changed by a later author through reclassification or when describing it to a new genus.
Blade - (Of leaves) The part of the leaf that is often flattened and broad, but which in a terete leaf is generally distinct from the leaf stalk or petiole but may resemble it closely: (Of the labellum) the enlarged and often ornate part of the labellum that may have 1 or more lobes and may appear insect-like.
Bract - A leaf-like structure that lacks a blade, and which is often much less developed than a leaf, being mostly small and supporting a flower, or encircling (sheathing) a stem.
Bracteate - Having bracts.
C
Calcicole - A plant that favours areas of limestone outcrop, being accustomed to soils with alkaline pH and high concentrations of Calcium ions.
Calli - Non-secreting glands that are found (mostly) on the labellum of some orchids.
Calyx - The lower whorl of flower parts, also known as the sepals.
Capitulum - A dense inflorescence in which the flowers are produced on very short stems (pedicels) and close together. The most familiar example is the flower of a daisy.
Caudicle - A stalk that joins the pollinia to the viscidium, and which is derived from the anther.
Cauline - (Of leaves) carried on the stem (compare to rosette)
Cilia - Fine hairs that are mostly found on the margin of an organ (usually the labellum or the leaves).
Ciliate - Bearing cilia.
Claw - A narrow stalk found at the base of a segment, most frequently used in orchids to refer to a slender stem at the base of the labellum which is readily distinguishable from the blade or enlarged part of the labellum.
Clinandrium - The cavity on the column where the anther is placed.
Column - The structure found in most orchids (and a few other plant families) which forms from a fusion of the female style with the male filaments, and which is among the most distinctive of structures in orchids.
Column foot - A fleshy extension of the base of the column which often acts as the point of fusion of the base of the sepals in those plants that have a column foot.
Conaliculate -
Conchiform - Shell-like or shell shaped.
Conduplicate - Folded along its length, and with each half flat (compare with plicate or pleated)
Connate - Having two or more of the same floral part fused together. Generally refers to sepals being fused together, mainly at the base, or along one edge (as in Cirrhopetalum).
Corm - An enlarged underground stem of several internodes; the underground equivalent of a pseudobulb.
Corymb - An inflorescence in which the rachis is not completely condensed and the pedicels are not originating in a whorl, but in which the flowers are produced in a single plane and often appear to be in a whorl. Compare with umbel.
Crenate - Having the margin scalloped, or shaped into regular, rounded teeth.
Crenulate - As for crenate, but with the marginal teeth smaller.
D
Deciduous - (of leaves) discarding the foliage at least once each season, and usually in response to particular environmental triggers (such as drought). May refer to other parts of the plant as well, but that use is much less common. (Compare to evergreen.)
Decurrent - Of an organ (such as a leaf) when it continues downwards (along the stem) below the point of attachment.
Decurved - Curving downwards (compare deflexed, recurved and reflexed).
Deflexed - Sharply bent downwards (compare decurved, recurved and reflexed).
Distichous - Arranged in two rows on opposite sides of the stem.
Dorsal - Of the upper side.
dorsal sepal - The odd sepal, usually placed nearest the column and not always on the upper side.
E
Ecallose - Without calli.
Elliptic - flat and oval in shape, with each end narrowed yet rounded off.
Epilith - A plant that generally grows upon rocks (or more usually in shallow pockets of moss, humus or leaf litter on a rocky substrate). Also known as a lithophyte.
Epilithic - Having the habit of an epilith.
Epiphyte - A plant that generally grows upon trees (or more usually in moss on a tree or on the coarse surface of bark).
Epiphytic - Having the habit of an epiphyte.
Evergreen - Retaining the leaves on a stem for more than one season (compare to deciduous).
F
Fasciculate - Produced in a cluster.
Filiform - Very slender.
Fimbriate - Fringed along the margin.
Foliose - Leaf-like. Also termed foliaceous
Fugacious - Falling or fading early, used in orchids mainly in reference to short-lived flowers (the 'one-day wonders' may have flowers that last for little more than a few hours).
G
Galea - A hooded or helmet-like structure formed of the dorsal sepal, and often with the petals fused to the dorsal sepal as well to form a cap over the column and often the labellum.
Geniculate - Knee-shaped, bent at right angles.
Gynostegium - another term for the column.
H
Hastate - Shaped like a spear-head.
Helical - Arranged in a spiral manner, such as leaves produced on a stem. Compare with distichous.
Hyaline - translucent or glassy in appearance.
Hypochile (hypochilium) - the basal part of the labellum when it is distinct from the apical (distal) part.
I
Inflorescence - the all-encompassing term for the structure bearing the flowers of the plant. See also raceme, scape, spike and panicle
K
Keiki - Small plants that will grow from unusual parts of the plant, generally inflorescences (as in Phalaenopsis, Epidendrum and Dendrobium) or on the stem (as in Dendrobium, Neobenthamia and the sarcanthids). The plural is keikies, and the word is derived from the Hawai'ian term for baby.
L
Labellum - The lip, or modified petal of the orchid flower, developed as a landing pad or attractant for pollinating insects.
Lacerate - Having the appearance of being irregularly cut or torn.
Lateral - Produced from the side. Mainly used in relation to an inflorescence or root that originates from the side of the stem, but shows no apparent relation to an axil. Compare to axillary and leaf opposed.
Leaf-opposed - Produced opposite the base of a leaf or its blade. Used mostly in reference to an inflorescence which is developed on the opposite side of a stem to the base of the leaf blade closest to it.
Lepanthiform - imbricating, ribbed and tubular
Ligule - A membranous or hairy structure produced at the top of a sheathing leaf base (leaf sheath), or at the base of the leaf blade. Most common in grasses and seen in very few orchids (e.g. Aracamunia).
Lithophyte - See epilith.
M
Membranous - Having a very thin texture.
Mentum - A chin-like extension of the base of some orchid flowers that is formed from the bases of the lateral sepals and their fusion to the column foot. Compare to a spur.
Monocarpic - Flowering and fruiting only once in the lifetime of an individual.
Monopodial - Having a growth habit or form in which the stem continues to grow upwards without termination. Compare to pseudomonopodial and sympodial
Murices - Short, hard-pointed tubercles or protuberances.
N
Non-resupinate - Not twisted. Used in reference to some orchids in which the flowers are produced in an 'upside down' manner, with the labellum uppermost and the dorsal sepal lowest in the flower. It should be noted that this is the original orientation of the flowers, and most species rotate the buds through 180 degrees during development.
O
Osmophore - A gland which secretes an odour (which may or may not be detectable to humans) that acts as a primary lure for the pollinator.
Ostia -
Ovary - The organ in which the immature seeds (as ovules) are produced, and which will become part of the fruit after fertilisation. In all orchids the ovary is placed below the calyx (termed inferior).
Ovate - flattened, yet egg-shaped in outline (one end braoader than the other, yet rounded at each end).
P
Palaeogeographic - In relation to the ancient layout of the geography. Derives from the study of continental drift and plate tectonics, and suggests that the orientation and arrangement of the contintnents and how they are joined has changed significantly over time.
Panicle - An inflorescence in which the stem (rachis) is branched, and each of the ultimate branches is a raceme.
Paniculate - Having a panicle for an inflorescence.
Pectinate - Comb-like.
Pedicel - The stalk of an individual flower.
Peduncle - The basal, unbranched part of the inflorescence, between the stem and the lowest pedicel or lowest branch of the rachis in a panicle.
Perianth - The collective term for the petals and sepals.
Perpendicular - At right-angles (90 degrees).
Persistent - Remaining in place.
Petal - The innermost whorl of the perianth, in orchids comprising two, generally identical structures (the petals) and the third highly modified and termed the labellum. In orchids, the term petal is generally restricted to use for the two structures that are identical and which show similarity to the sepals.
Petiolate - Having a petiole.
Petiole - The stalk of a leaf, often narrow or filiform, and located between the stem and the blade.
Pheromone - A chemical which causes enhanced sexual activity in animals.
Phytogeographic - The study of the distribution of related groups of plants (mostly families, genera or species).
Pleated - Folded lengthwise more than once.
Plicate - Pleated.
Pollinarium - The entire male structure of the flower as removed and carried by the pollinator during pollination.
Pollination - THe process whereby pollen is transferred to the stigma of a flower.
Pollinator - The carrier that takes pollen from the anther to the stigma, in most Orchidaceae this is an insect.
Pollinia (pollinium) - The aggregated, coherent mass of pollen grains as found in orchids.
Porrect - Pointing outwards and forwards.
Pseudobulb - The thickened, bulb-like structures of sympodial orchids that consist of several nodes.
Pseudocopulation - A pollinating process in which a male insect is fooled into attempting to mate with the flower (which mimics the female of the insect species by the use of pheromones and/or appearance) and in the process of trying to mate with the flower collects and distributes the pollinarium.
Pseudomonopodial - Having a habit or form in which the stem growth continues upwards in sporadic bursts, without a distinct break of stem production. Compare to sympodial and monopodial.
R
Raceme - An inflorescence in which the flowers are borne on a single, unbranched stem (the rachis), with the pedicel of the flower attached directly to the rachis.
Rachis - The 'stem' of an inflorescence, including the branches, which provides support to the flower or flowers holding them clear of the plant and in view of the pollinator.
Ramicaul - The slender, elongate stem supporting the leaf blade in members of the Pleurothallidinae.
Recurved - curved backwards or upwards.
Reflexed - Bent sharply backwards.
Resupinate - Rotated, as in the flowers of most orchids which are rotated through 180 degrees during development to place the labellum at the lowest side of the flower. Compare with non-resupinate.
Rhizome - An underground stem with nodes and roots and which can form shoots. Generally not thickened or modified to act as a storage organ to any great extent.
Rigent -
Rosette - A circular or rounded arrangement of leaves at or near the ground surface and in a low position on the stem.
Rostrate - Possessing or having a beak-like process.
S
Saccate - Sac-like or bag-like
Saprophyte - a growth habit in which nutrient for the plant is derived from a relationship between the plant and fungi that feed on rotting plant materials.
Scape - term applied in orchids to a solitary-flowered inflorescence. Also applied in more general terms to the peduncle.
Scutiform - Shield-shaped.
Sepal - A member of the lowest whorl of perianth segments. The sepals' primary function is to protect the developing flower bud, but in most orchids they have also become involved in the attraction of pollinators by being patterned and shaped accordingly.
Serrate - Bearing sharp-tipped, forward-pointing teeth.
Sessile - Lacking a stalk, petiole or pedicel.
Spicate - Being borne in a manner suggesting arrangement on a spike.
Spike - A term used in error for the inflorescence of orchids. No orchid is capable of having a spike, as the spike has the flower calyx (or similar) attached directly to the rachis. As orchids possess an inferior ovary and all species have a pedicel (within which the ovary is embedded), the flower is always held away from the rachis.
Sporadic - Happening at indeterminate (and often unequal) intervals. Mainly used in reference to plants that flower in relation to some environmental variable rather than in response to seasonal change.
Spur - A slender, hollow projection developed from a single floral segment (but sometimes with spurs on a number of separate segments on a single flower). Compare to mentum.
Stelids -
Stigmaphores -
Stipe - A stalk derived from the rostellum which attaches the pollinia to the viscidium (similar to a caudicle).
Stolon - A basal subterranean stem that forms roots and shoots at intervals.
Stoloniferous - Having the habit of bearing stolons.
Subulate - Shaped like an awl, in having the apex sharply pointed, and the shape tapering from the apical point to the base of the structure.
Successional - Being produced in a successive manner.
Successive - Happening in a continual series, such as flowers opening one or few at a time along an inflorescence.
Synanthus - With the flowers: the flowers are produced at the same time as the leaves.
T
Tepal - The collective term applied to the petals and the sepals when these structures are similar to each other.
Terete - (Of leaves) circular in cross-section, without flattened surfaces.
Terminal - Occurring at the end, such as the flowers occurring from the apical point of the stem.
Trifid - Divided into three parts.
Tuber - A thickened underground stem. In this work applied equally to true tubers (such as potatoes) which may not occur in orchids and tuberoids, which are swollen tuber-like roots.
Tuberculate - Having tubercles - warts or nodular swellings.
Tunic - a membranous, sheathing layer of tissue.
U
Umbel - An inflorescence in which the stem is not branched, and the rachis is condensed to the point that all flowers are produced in a whorl. The occurrence of this type of inflorescence in some genera (such as Cirrhopetalum) is not substantiated, and most inflorescences of this type are condensed, but still produce the pedicels in a helical or similar pattern, not a whorl. The comparable inflorescence produced in orchids is called a corymb.
V
Variegated - Marked with a number of different colours, often in a repetitive pattern.
Vermiform - worm-like.
Viscidium - The sticky and adhesive tissue attached to the pollinia which is the method by which the pollinia are attached to the pollinator.
W
Whorl - The term used to describe having a number (more than two, generally 3 in orchids) of the same part arising from the same place. May refer to leaves coming from a stem, or more frequently in the case of orchids, the sepals and petals of the flower.
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