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Term	Definition
Decussate leaves	Referring to opposite leaves arranged with each succeeding pair at right angles to the pairs below and above them.
Dehisce (dehiscent)	Splitting open at maturity, usually applied to a fruit that opens to release seeds but other structures, such as sporangia may also be called dehiscent.
Dehiscent fruit	Referring to fruits that open via an operculum (= lid like in a teapot) at maturity.
Deltate	Shaped like an equilateral triangle. Same as deltoid.
Dentate (diminutive = denticulate)	Toothed; having a margin with sharp teeth oriented at right angles to the central axis of the structure bearing them.
Determinate inflorescence	A type of inflorescence in which the terminal or central flower opens first; for example in cymes.
Diadelphous stamens	Stamens united into two, often unequal, sets; e.g., those of many Fabaceae, which have nine stamens in one set and one stamen in the other.
Dialisépalo	Se refiere al cáliz que posee los sépalos libres. Opuesto a gamosépalo
Diaspore	Referring to the dispersal unit of a plant (e.g., the inflorescence, part of an inflorescence, the fruit, part of a fruit, or a seed).
Dichasial cyme	A determinate inflorescence in which growth of the central axis is terminated by a flower that opens first and each pair of branches subtending this flower then is terminated by a single flower.
Dichogamy (dichogamous)	Referring to a flower in which pollen is released and stigmas are receptive at different times.
Dichotomous growth	In morphology, a axis that successively forks into two more or less equal parts.
Dichotomous key	A dichotomous key aids in the identification of a family, genus, or species by progressively giving choices based on different states of a character (e.g., leaf complexity with the character states being leaves simple or leaves compound). A series of similar questions eventually leads to a possible identification of the plant in hand but this should be confirmed by reading descriptions, comparing with collections in a herbarium, or with images from various sources (e.g., Google images). If a monograph or flora exists for the group it is identified as they can be consulted to confirm the determination.
Dicliny (diclinous)	Referring to species with separate staminate and pistillate flowers. Dioecious and monoecious plants are examples of diclinous plants. Compare with monocliny.
Dicotyledon (dicot)	One of the two main groups of angiosperms usually characterized by having two cotyledons, net-veined leaves, and flower parts generally in fours or fives. In the classification of Cronquist (1981), this class is called Magnoliopsida. Dicotyledons are not monophyletic in the classfication system of the APG.
Didynamous stamens	With two pairs of stamens of unequal length.
Differentiated anthers	Referring to anthers that bear two types of pollen: 1) fertile pollen that is transferred to other flowers to effect fertilization and 2) sterile (= fodder) pollen that serves as a pollinator reward. The two types of pollen may differ in their ability to germinate, in their color (fodder pollen is often yellow), and in their morphology (e.g., the fertile anthers of Couroupita guianensis are in monads and the sterile ones are in tetrads), and their location (e. g., the fertile anthers are near the stigma and the sterile ones are in a group separate from the stigma in many species of Swartzia.
Diffuse roots	A root system that consists of many more-or-less branches of equal sizes, i.e., there is no taproot.
Digging tools	Tools used to dig up the underground parts of plants. These kinds of tools, which can be purchased in hardware stores anywhere, come in all shapes and forms but we prefer the dandelion digger shown in the upper part of this image. For more information about plant collecting see Tropical Plant Collecting: From the Filed to the Internet. This book can be purchased at: http://tecceditora.com/ or Amazon.com.
Digitate	Arranged as fingers on a hand; in the Cyperaceae and Poaceae, referring to such an arrangement of spicate branches of an inflorescence; for application to leaves, see palmate.
Dilated	Spread out or expanded, e.g., the base of a filament in relation to the more constricted apex.
Dimorphic	Occurring in two forms; e.g., in the Mimosaceae, different flower shapes in the same inflorescence. Compare with heteromorphic and monomorphic.
Dioecy (dioecious)	Describing a sexual condition of a species that bears only functionally staminate flowers on some plants and only functionally pistillate flowers on other plants. Compare with monoecious.
Diplochory	Seed dispersal in two different ways, e.g., a seed is eaten by a monkey and then is moved further by ants carrying it away from the monkey's dung.
Diploid	Having two sets of chromosomes; e.g., a plant with a diploid chromosome number of 2n = 24 has two sets of 12 each (one from the paternal and the other from the maternal parent).
Diplostemony (diplostemonous)	With two series of stamens; those of the outer series inserted opposite the sepals, those of the inner series inserted opposite the petals. Compare with obdiplostemonous. Diplostemony is sometimes very difficult to determine in flowers at anthesis but becomes apparent with microtome and SEM studies of bud development of obdiplostemony which is also applicable to diplostemony (Endress, 2010).
Disc	A fleshy, lobed, or annular nectariferous structure found within flowers; the position can be either outside or within the stamens. Preffered spelling is disc. Not to be confused with disk flower in the Asteraceae.
Disciform capitulum (head)	An inflorescence of Asteraceae with only disk flowers.
Discoid capitulum (head)	Inflorescence of Asteraceae with only disk flowers. Same as disciform capitulum.
Discolor (adj. = dicolorous)	When two sides of an organ, such as a leaf blade, are different colors.
Discolor (adj. = discolorous)	When two sides of an organ, such as a leaf blade, are different colors.
Discolor (adj. = discolorous)	When two sides of an organ, such as a leaf blade, are different colors.
Disk flower	An actinomorphic flower with a tubular corolla found in Asteraceae. Compare with ray flower.
Dispersal (disperse)	The transport of fruits, parts of fruits, or seeds away from a parent plant by agents such as water, wind, bats, other mammals, ants, scarab beetles, etc. The act of dispersing a diasporte.
Distal	Remote from the place of attachment. Opposite of proximal. Same as apical.
Distal	The part of an organ furthest away from the point of attachment.
Distichous	Referring to structures that are arranged in two rows; usually referring to the way in which leaves or bracts are inserted on an axis. Same as two-ranked.
Distyly (distylous)	A type of heterostyly in which flowers with both long and short styles occur in different individuals of the same species.
Diurnal	Appearing during the day, such as a flower at anthesis.
Diurnal	Appearing during the day, such as a flower at anthesis.
Divergent	Referring to an organ, such as a flower or the thecae of an anther, that spreads away from the axis to which it is attached.
Domatium (pl. domatia)	A cavity or chamber, mostly associated with leaves, that usually serves as home for ants or mites.
Domatium (plural = domatia)	Referring to axillary cavities, enclosed chambers, hollow stems, hollow petioles, modified stipules, or clusters of trichomes that harbor ants, mites, and other invetebrates. All of these structures are called domatia.
Double calyx	A calyx with two apparent whorls; e.g., the calyx of Amphilophium painculatum.
Drip tip	A long, tapered leaf blade apex that is thought to help water drain form the blades thereby reducing the number of epiphylls that become established on the leaf.
Drupe	A single-seeded, indehiscent fruit with three distinct layers: the thin excocarp, often fleshy mesocarp, and the often woody or bony endocarp.
Drying frames	Referring to wood or metal frames upon which a plant press is placed. The heat source can be propane gas, light bulbs, heating strips, or hot plates. The opening in the top of the frame should be covered by a wire mesh to make sure that nothing falls onto the heat source and catches fire. The size of the frame depends upon the number of specimens collected each day and the distance from the plant press to the heat source is determined by the intensity of the heat source. For more information about plant collecting see Tropical Plant Collecting: From the Filed to the Internet. This book can be purchased at: http://tecceditora.com/ or Amazon.com.
Duplicate collection	Referring to a collection number that is represented by more than one specimen. For example, a collector working out of a host herbarium should collect at least three collections of plants they are not able to identify 1) the first stays at the host herbarium, 2) the second is sent to a specialist, and 3) the third is archived in the herbarium of the collector. Two duplicates can be made if the collector is able to identify the collection to species and more are usually made if the collection is of special interest. For more information about plant collecting see Tropical Plant Collecting: From the Filed to the Internet. This book can be purchased at: http://tecceditora.com/ or Amazon.com.
Dysozoochorous	A type of secondary seed dispersal in which some of the diaspores are carried away and intentionally buried or stored (cached) by scatter-hording animals such as agoutis (Dasyprocta spp.) while the other diaspores are eaten and digested, e.g., the dispersal of Brazil nut seeds by agoutis. Same as scatter-hoarding.
Ecology	Dome-like granitic outcrops common on the Guayanan Shield of northeastern South america. Inselbergs are sparsely covered by vegetation which often occurs as clumps here-and-there and separated by bare rocks. Low gnarled trees of species of Clusia are often dominant in this vegetation type. Most inselbergs occur below 1000 meters altitude.
Egg	The female reproductive part of a plant. In the flowering plants (angiosperms), the egg is located at the micropylar end of the megagameophyte flanked on each side by a synergid cell. After fertilization the ege develops into the embryo and the embryo develops into the adult plant.
Elaiosome	A fleshy, oily outgrowth of the seed coat that often attracts ants for dispersing the seeds. Compare with aril and sarcotesta.
Elaiosome	A fleshy, oily outgrowth of the seed coat that is eaten by ants. In the process, the ants often disperse the seeds away from the mother plant.
Electronic key	An electronic key takes advantage of a database to facilitate the identification of an unknown plant to family, genus, or species. Electronic keys generally consist of four boxes as follows: (1) characters and character states upper left hand box), (2) taxa included in the keys, e.g., all of the genera, species, and infraspecific taxa in a plant family or all of the taxa in a Flora (upper right hand box). As choices are made species that do not have given characters are eliminated and appear in the lower right hand box, 3) all of the characters and character states that have been used while progressing through the key (lower left hand box), and 4) all of the taxa that have been rejected as a possible determination (lower right hand box). The advantages of electronic keys are 1) the key can entered no matter what characters are present in the plant being identified, 2) links can be made to electronic glossarys so the meaning of the characters can be understood by consulting their definations and seeing illustrations of them, 3) links can be made to family, generic, and species pages to confirm or reject determinatiions, and 4) a determination is always reached which ideally is a single taxon but if more than one taxon, the possibilities can be accepted or rejected based on viewing the taxon pages.
Elliptic	Referring to the outline of essentially two-dimensional structures, such as leaves, bracts, petals, and sepals, which are widest at or near the middle. Elliptic shapes are divided based on their length/width ratios. An elliptic shape has a length to width ration from 2:1 to less than 3:1.
Emarginate	Markedly notched, such as the apex of a leaf or other structure.
Embryo	The young sporophytic plant found inside of the seed.
Embryo	A young seed plant found within the seed, a dicotyledon embryo consists of the hypocotyle, cotyledons (usually two), and the epicotyl.
Embryo air chamber	Referring to an embryo with a chamber inside of the seed caused by bowed cotyledons.
Embryo macropodial (= cotyledons absent)	Massive embryo that shows no obvious cotyledons. Cotyledons absent is the preferred term.
Embryo sac	The female gametophyte of angiosperms (flowering plants). Same as megagametophyte.
Emergent tree	A species of tree in which adult individuals exceed the more or less continuous canopy layer of a forest.
Emergent tree layer	A hypotherical layer in tropical forests made up of species of the tallest trees with crown emerging above the canopy tree layer.
Empheral	A temperate zone plant that sends out leaves and photosynthesizes in the spring before the leaves of the trees appear. During this time the plant produces and stores enough carbohydrate to allow it to flower the following spring. Not long after flowering, the plant wilts and remains inconspicuous until the next spring.
Enclosed bud	A bud that is either completed surrounded by the calyx or that has a pore-like or slit-like opening at early developmental stages.
Endemic	Native to and restricted to a given geographic region or to a given soil type or other habitat.
Endocarp	The innermost layer of the fruit wall. Compare with pericarp.
Endocarp buttress	A raised, somewhat rounded ridge running the length of the endocarp in the fruits of species of Grias.
Endosperm	The energy-rich food supply of the seed that is formed by the fusion of the sperm and polar nuclei of the female gametophyte, initially surrounds the embryo, and is often apparent in the seed; some seeds, however, do not have any apparent endosperm.
Endosperm	The energy-rich food supply of the seed that is formed by the fusion of the sperm and polar nuclei of the female gametophyte, initially surrounds the embryo, and is often apparent in the seed; some seeds, however, do not have any apparent endosperm.
Entire	Referring to a margin of a leaf, sepal, or petal that is not interrupted by teeth or lobes.
Eophyll	The first true leaf of a seedling; i.e., the first leaf to appear after the cotyledon(s).
Eophyll	The first leaves of a seedling, other than cotyledons, which may or may not be similar to adult leaves in form and position.
Ephemeral	Lasting a short time; for example, a spring emphemeral in temperate regions that flowers and sets fruits before the canopy trees leaf out or a tree such as species of Tabebuia that flower for only a few days, thus the flowers are ephemeral. Same as evanescent.
Epicalyx	A whorl of bracts on the pedicel, similar to sepals, and inserted below the calyx; most commonly found in species of Malvaceae..

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