Plant Taxonomy


(Definitions and most etymologies from Webster's Third New International Dictionary, Springfield, G & C Merriam, 1966, except where (h) indicates Harris, James G. & M. L., Plant Identification Terminology: An illustrated Glossary, Spring Lake Publishing, Spring Lake UT, 1994. Line drawings by NAU students of BIO415, Spring semester, 2002, & Noel Benson.)

Image Term Definition Derivation
1st Glume
2nd Glume
Accessory tissue
Accrescent involucre
Accrescent involucre
Achene a small, dry, indehiscent one-seeded fruit developed from a simple ovary and usually having a thin pericarp attached to the seed at only one point
Actinomorphic radially symmetrical -- used of organisms, organs, or parts capable of division into essentially symmetrical; halves by any longitudinal palne passing through the axis; compare zygomorphic
Adnate grown together, used especially of unlike parts
Age and Area Hypothesis
Aggregate of a flower: clustered in a dense mass or head; of a fruit: formed from the several separate or fused ovaries of a single flower
Aggregate of follicles
Air bladder
Alkaloid any of a very large group of organic bases containing nitrogen and usu. oxyygen that occur esp. in seed plants for the most part in the form of salts with acids (as citric, oxalic, or sulfuric acid), most of the bases being colorless and well crystal lized, bitter tasting, complex in structure with at least one nitrogen atom in a ring (as a pyrole, quinoline, or indole ring), and optically and biologically active, many of the bases or their salts being used as drugs (as morphine and codeine)
Alternate arranged first on one side and then on the other at different levels or points along an axial line
Ament an indeterminate spicate inflorescence bearing scaly bracts and apetalous unisexual flowers (as in the willow) L. amentum thong, strap
Anther the part of the stamen in seed plants that consists of microsporangia, develops and contains pollen, and though sometimes sessile, is usually borne on a stalk
Anthers unilocular
Anthocarp a fruit with some portion of the flower besides the pericarp persisting, as in a pome with the fleshy perianth tube surrounding the pericarp (h)
Apex the pointed end : tip
Apical meristem meristem located at the apex of a root or shoot and responsible for increase in length of the organ
Apical ovule
Apical pore
Areole a small pit or cavity (as that from which spines arise in cacti)
Aril an exterior covering or appendage of certain seeds that develops after fertilization as an outgrowth from the funiculus and envelopes the seed prob. fr. NL arillus, fr. ML., raisin, grape seed
Aromatic gland
Auricle an ear-shaped appendage (as at the base of the leaf blade of many grasses)
Apocarpous having the carpels of the gynoecium separate
Awn one of the slender bristles that terminate the glume s or bracts of the spikelet in barley, oats, some varieties of wheat, and other grasses
Axil the distal usu. upper angle or point of divergence between a branch or leaf and the axis from which it arises
Axile belonging to or situated in the axis
Axile ovule
Axile placentation ovules attached to the central axis of an ovary with two or more ovules (h)
Axillary bud
Axillary cyme
Axis the stem of a plant : the longitudinal support on which organs are arranged often including also the root, esp. a taproot : the hypothetical central line of any body or organ
Basal proceeding from the base of a stem, from a rootlike stem, or from a stem that does not rise above the ground
Basal bract
Basally connate
Basally oblique
Basal ovule
Bases fused
Berry any simple fruit that has a fleshy pericarp (as the currant, grape, gooseberry, cranberry, tomato, or banana)
Biconvex convex on both sides
Bilabiate having two lips
Bipinnate twice pinnate
Bisexual possessing characters typical of both sexes
Blade a leaf of a plant esp : a leaf of an herb or more narrowly of a grass c(1) : the expanded portion of a leaf or a plant organ resembling a leaf --distinguished from petiole (2) : the broad terminal part of certain petals -- distinguished from claw
Boreal of, relating to, or constituting a terrestrial biogeographic division comprising the northern and mountainous parts of the northern hemisphere in which mean temperature during the six hottest weeks does not exceed 64.4o F. and being equiva lent to the Holarctic region exclusive of the Sonoran and Transition zones and corresponding Old World areas
Brachiate having widely spreading branches arranged in altenating pairs -- compare DECUSSATE
Bract a somewhat modified leaf associated with the reproductive structures of a plant: as a: a leaf frrom the axil of which a flower or floral axis arises   b : a leaf borne on the floral axis itself (as one subtending the flower or flower cluster) ordinarily smaller than a foliage leaf but occas. large and showy and simulating petals (as in the fever tree and flowering dogwood) --called also bracteole, bractlet; see GLUME, INVOLUCRE, spathe; compare scale
Bracteole : a small bract; esp : one on a floral axis -- called also bractlet NL bracteola, fr. L, thin gold leaf, dim of bractea, brattea gold leaf
Bractlet : bracteole
Branch a shoot or secondary stem growing from the main stem
Branched hairs
Bristly hair
Buffered in the case of Nymphaeaceae: plants are protected from extreme fluctuations in temperature by the slower rate of change in the body of water (nb)
Bulb a mass of overlappiing membranous or fleshy leaves on a short stem base enclosing one or more buds that may develp under suitable conditions into new plants and constituting the resting stage of many plants (as lily, onion, hyacinth, tulip) distingui shed from corm, rhizome, tuber
Calyx the outer set of floral leaves making up the external part of the flower and consisting of separate or fused sepals ttha are usu. green and foliaceous but often colored like the corolla -- see corolla
CAM Crassulacean Acid Metabolism
Capillary bristle
Capitulate collected into small capitula (see below)
Capitulum a simple racemose inflorescence in which the primary axis is shortened and dilated forming a rounded or flattened cluster of sessile flowers (as in the buttonbush and in all composite plants) -- called also head
Capsule in seed plants: a dry dehiscent usu. many-seeded fruit composed of two or more carpels and releasing seed at maturity through pores or by breaking into valves--compare pod
Carbonized wall
Carpel one of the structures in a seed plant comprising the innermost whorl of a flower, functioning as megasporophylls, and collectively constituting the gynoecium--compare pistil
Carpophore a slender often forked prolongation of a receptacle or pistil or both which develops as the fruit ripens and from which the ripened carpels are suspended (as in members of the genus Geranium and in the Umbelliferae)
Caryopsis a small one-seeded dry indehiscent fruit with a thin membranous pericarp adhering so closely to the seed that fruit and seed are incorporated in one body forming a single grain (as in wheat, barley, Indian corn, and other grasses)
Catkin an ament esp. long and densely crowded with bracts
Cereal a plant (as a grass) yielding farinaceous seeds suitable for food (as wheat, maize, rice)
Chromosome one of the more or less rodlike chromatin-containing basophilic bodies constituting the genome and chiefly detectable in the mitotic or meiotic nucleus that are regarded as the seat of the genes, consist of one or more intimately associated chromatid s functionintg as a unit, and are relatively constant in number in the cells of any one kind of plant or animal
Circinate characterized by hor having the form of a flat coil of which the apex is the center -- used esp. of arrangements of plant parts in vernation and of developing fern fronds
Circumscissile dehiscing by a transverse fissure around the circumference -- compare loculicidal
Claw the slender, prolonged basal portion of certain petals (as in the pink) --compare blade
Clawed having claws (see above)
Column the united monadelphous stamens in mallows b : the united androecium and gynoecium in orchids
Compound composed of or produced by the union of several elements, ingredients, parts, or things b : involving combination
Concave arched in : curving in
Cone a mass of ovule-bearaing or pollen-bearing scales or bracts in trees of the pine family and in cycads arranged usu. on a somewhat elongated axis : a carpellate or staminate strobilus; esp : the carpellate strobilus of pine and related trees < b>b : any of several flower or fruit clusters suggesting a cone (as of the hop or certain magnolias)
Connate congenitally united
Connate bractlet
Connate by connectives
Connate carpel
Connivent converging but not fused into a single part (distinguished from connate
Contractile root
Corm modified underground stem base bearing membranous or scaly leaves and buds and acting as a vegetative reproductive structure in certain monocotyledonous plants (as gladiolus and crocus) -- distinguished from bulb; compare < a href="#tuber">tuber
Corolla the inner set of floral leaves that immediately surround the sporophylls, consist of separate or fused petals, and are often highly colored in contrast to the calyx but sometimes inconspicuous or even absent NM, fr. L, small garland, dim. of corona
Corona an appendage or series of united appendages borne on the inner side of the corolla in certain flowers (as in the daffodil, jonquil, and milkweed) and often resembling an additional whorl of the perianth
Cotyledon the first leaf or one of the first pair or whorl of leaves developed by the embryo in seed plants and in ferns and related plants that functions primarily to make stored food in the endosperm available to the developing young plant but in some cases acts as a storage or photosynthetic organ
Creeping tending to spread over the ground or other substrate
Cross-shaped . . . two intersecting lines or bars usu. of equal or approximately equal length and crossing at or about their midpoints
Crumpled wrinkled, creased, or bent out of shape by or as if by pressing, folding, or crushing
Culm the jointed stem of a grass usu. hollow except at the often swollen nodes and usu. herbaceous except in the bamboos and other arborescent grasses; also : one of the solid stems of sedges, rushes, and similar monocotyledonous plants
Cyathium an inflorescence consisting of a cuplike involucre with the flowers arising from its base (as in the poinsettia).   more...
Cyme 1 : an inflorescence in which the main and secondary axes always terminate in a single flower whether one flower is produced (as in the wood anemone) or the inflorescence is continued by secondary and tertiary axes (as in the buttercup) 2 : any flower cluster of the cyme type containing several or many flowers (as in pink or phlox) with the first-opening central flower terminating the main axis, subsequent flowers developing from lateral buds, and the inflorescence therefore exhibiting determinate growth --compare corymb, raceme
Deciduous falling off or shed at the end of the growing period
Decussate arranged in pairs each at right angles to the next pair above and below -- compare brachiate
Dehiscence a bursting open: as a (1) : the bursting open of a capsule, pod, or silique at maturity either between the carpels, through the middle of the carpels, or in some other manner -- compare circumscissile,  ;loculicidalsepticidalseptifragal (2) : the opening of an anther for the discharge of pollen (as by longitudinal slits or pores)
Dehiscent characterized by dehiscence
Desert a region in which the vegetation is so scanty as to be incapable of supporting any considerable population (as a region perpetually cold or covered with snow or ice or a region located in the interior of a continent and characterized by scanty rainfa ll esp. of less than 10 inches annually)
Determinate growth in which the axis being limited by the devlopment of the terminal flower bud or other reproductive structure does not continue to elongate indefinitely (as in a cymose inflorescence and in certain mosses)
Diadelphous of stamens: united by the filaments into two fascicles
Dichotomous dividing into two parts or groups
Dichotomous venation
Dimorphic having two forms
Dioecious having staminate and pistillate flowers borne on different individuals
Disciform of round or oval shape
Disciform head
Discoid relating to or having a disk: as a of a composite floret : situated in the floral disk : being a disk floret b of a composite flower head > having only tubular florets
Discoid head having only tubular florets
Disk the central portion of the flower head of a typical composite composed of closely packed tubular flowers
Disk floret one of the tubular flowers in the disk of a composite plant
Dissected deeply divided into many narrow segments (h)
Dissepiment a separating tissue : PARTITION : SEPTUM
Distinct separate, not attached to like parts (h)
Drupe a one-seeded indehiscent fruit having a hard bony endocarp, a usu. fleshy mesocarp, and a thin epicarp like a skin (as in the cherry, plum, and peach) or dry and almost leathery (as in the almond)
Drupelet one of the individual parts of an aggregate fruit (as the raspberry)
Elongated style
Emergent (or "emersed") rising from or standing out of water (h)
Endemic restricted to or native to a particular area or region : INDIGENOUS -- used of kinds of organisms; compare exotic
Entire having the margin continuous or not broken by divisions, teeth, or serrations
Ephedrine a white crystalline alkaloid . . . extacted esp. from mahuang or made synthetically and used often in the form of a xalt (as a sulfate) chiefly in relieving hay fever, asthma, and nasal congestion
Epidermal of, relating to, or arising from the epidermis [which is] a layer of primary tissue in higher plants that is commonly one cell thick, often cutinized on its outer surface, and continuous in young plants except over the stomata, that provides protecti on to underlying parts against mechanical injury and desiccation, and that is largely replaced (as by periderm or exodermis) in older plants except on leaves and herbaceous stems
Epiphyte a plant that grows upon another plant (as a tree) nonparasitically or sometimes upon some other object (as a building or telegraph wire), derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it . . .
Episepalous growing on or adnate to the sepals
Equitant overlapping each other transversely at the base (as in an iris)
Estipulate without stipules
Ethereal oil essential oil : any of a large class of volatile odoriferous oils of vegetable origin that impart to plants odor and often other chatacteristic properties, that are obtained from various parts of the plants (as flowers, leaves, or bark) by steam dist illation, expression, or extraction, that are usu. mixtures of compounds (as terpenoids, aldehydes, or esters), and that are used often in the form of essences in perfumes, flavoring materials, and pharmaceutical preparations : volatile oil; distinguished from fatty oil and fixed oil
Exudate exuded matter fr. exude: to ooze out slowly in small drops through openings (as pores) . . . b : to flow slowly out : issue slowly forth
False indusium
Feathery style
Female cone
Fibrous containing, consisting of or like fibers
Filament the anther-bearing stalk of a stamen
Filaments connate
Filiform floret
Flagellum (pl. flagella) a long tapering process that projects singly or in groups from a cell or microorganism, is possibly equivalent to a much enlarged cilium, and is the primary organ of motion of flagellated protozoans and many algae, bacteria, and zoospores <.b>4 : a long slender shoot (as a stolon or runner) of a plant
Fleshy receptacle
Floret a single flower of a multiple -flowered inflorescence; esp b one of the small individual flowers that make up the head of a comjposite plant -- compare DISK FLOWER, RAY FLOWER
Follicle a dry dehiscent one-celled, many-seeded, and monocarpellary fruit (as that of the peony, larkspur, or milkweed) differing from a pod or legume in opening along only one (as the inner or ventral) suture
Free not united or combined with something else; distinct, separate
Fritillary a plant of the genus Fritillaria
Fruit the reproductive body of a seed plant consisting of one or more seeds and usu. various protective and supporting structures fr. L fructus past part. of frui to enjoy, have the use and enjoyment of
Fused mingled, blended, integrated
Fused carpel
Gametophyte the individual or generation of a plant exhibiting alternation of generations that bears sex organs, constitutes the major part of the plant body in most algae, fungi, and mosses, exists as an independent transitory thalloid body in ferns and related plants, and is reduced to a microscopic or rudimentary structure in see plants -- distinguished from sporohphyte
Glandular hairs
Glochid glochidium : a barbed hair or spine (as on the massulae of a water fern or on some cacti)
Glume one of the two empty bracts at the base of the spikelet in grasses
Green having the color of growing fresh grass or of the emerald
Halophyte a plant that grows naturally in soils having a high content of various salts, that usu. resembles a true xerophyte and that occurs in many families (as Chenopodiaceae, Compositae, Plumbaginaceae) -- compare mesophyte
Head capitulum
Helophyte a perennial marsh plant having its overwintering buds under water -- compare hydrophyte NL, fr. Gk helos marsh
Heterosporous characterized by the production of asexual spores of more than one kind
Homosporous characterized by the production by various plants (as the club mosses and horsetails) of asexual spores of only one kind
Host a living animal or plant affording subsistence or lodgment to a parasite
Hydrophyte a vascular plant growing wholly or partly in water; esp : a perennial aquatic plant having its overwintering buds under water b : a plant requiring an abundance of water for growth and growing in water or in soil too waterlogged for most other plants to survive -- compare mesophyte, xerophyte
Husk the outer covering of a kernel or seed esp. when dry and membranous
Hygroscopic sensitive to moisture b : induced by moisture
Hypanthium an enlargement of the usu. cup-shaped receptacle bearing on its rim the stamens, perals, and sepals of a flower and often enlarging and surrounding the fruits (as in the rose hip)
Imperfect DICLINOUS: having the stamens and pistils in separate flowers -- compare MONOCLINOUS, MONOECIOUS, DIOECIOUS
Inferior of a part of a plant a : situated below another organ: (1) of a calyx : free from the ovary (2) of an ovary : adnate to the calyx or other floral envelope
Inferior ovule
Inflorescence the mode of development and arrangement of flowers on an axis (2): a floral axis with its appendages : a flower cluster or sometimes a solitary flower
Involucral bract
Irregular of a flower or its parts : lacking uniformity; specif : zygomorphic (or) bilaterally symmetrical; said of a flower in which all parts are not similar in size and arrangement on the receptacle (compare regular, and see zygomorphic) (h)
Lateral vein
Latex a milky usu. white fluid of variable compostition that is usu. made up of various gum resins, fats, or waxes and often a complex mixture of other substances frequently including poisonous compounds, this is found in or produced by cells of plants esp of the Asclepiadaceae but also of the Apocynaceae, Sapotaceae, Euphorbiaceae, Papaveraceaea, Moraceae, and Compositae, and that yields rubber, gutta-percha, chicle, and balata as its chief commercial products
Ligulate floret
Ligulate flower
Ligulate head
Locule (loculus) one of the cells of the compound ovary of a plant   (2) : the cavity of a pollen sac
Loculicidal dehiscent longitudinally so as to bisect each loculus --compare circumscissile, septicidal
Long shoots
Marginal placentation
Mesophyte a plant that grows under medium conditions of moisture -- compare hydrophyte, #xerophyte
Mericarp one of the two carpels that resemble achenes and form the schizocarp of an umbelliferous plant
Mesic of a habitat : having or characterized by a moderate amount of moisture : neither hydric not xeric; of a plant or flora : mesophytic Gk mesos middle
Midvein midrib : the central vein of a leaf
Milky sap
Monadelphous united by the filaments into one group usu. forming a tube around the gynoecium
Monocarpic bearing fruit but once and dying--used esp. of annual and biennial flowering plants; compare century plant
Monocarpous having a single ovary
Monoclinous having the stamens and pistils in the same flower -- compare DICLINOUS, MONOECIOUS, DIOECIOUS
Monoecious having pistillate and staminate flowers on the same plant
Monophyletic developed from a single common parent form
Monopodial having or involving offshoots from a main axis
Motile exhibing or capable of movement
Mucilage cell
Mycorrhiza the symbiotic association of the mycelium of a fungus (as various basidiomycetes and ascomycetes) with the roots of a seed plant (as various conifers, beeches, heaths, and orchids) in which the hyphae form an interwoven mass investing the root tips or penetrate the parenchyma of the root
Naked floret
Naked receptacle
Neuter having no generative organs
Node the often swollen or otherwise modified point on a stem or similar structure at which a leaf or leaves are inserted
Nucleus an element of the protoplasm of most plant and animal cells that is regarded as an essential agent in their metabolism, growth, and reproduction and in the transmission of hereditary characters and that typically consists of a more or less rounded ma ss of nucleoplasm made up of a hyaline ground substance in which is suspended a network rich in nucleoproteins from which the mitotic chromosomes and one or more nucleoli condense, the whole being enclosed by a nuclear membrane
Nut a dry indehiscent one-seeded fruit (as an acorn, hazelnut, or chestnut) with a woody pericarp developing from an inferior syncarpous ovary
Nutlet a small nut-like fruit (as of many plants of the family Boraginaceae)
Ocrea a tubular sheath around the base of the petiole consisting of a single stipule in the red clover or a pair of coherent stipules in the buckwheat family (Polygoniaceae)
Opposite situated in pairs on an axis each being separated from the other by half the circumference of the axis (2) of floral parts : SUPERPOSED (3) situated side by side
Ovary the enlarged rounded usu. basal portion of the pistil or gynoecium of an agiospermous plant that bears the ovules and consists of a single carpel or of several united carpels
Ovary inferior
Ovary superior free from the calyx or other floral envelope
Ovary wall
Ovule a rounded outgrowth of the ovary in seed plants that develops into a seed usu. only after fertilization and that consists of an embryo sac borne centrally within a nucellus, the latter surrounded by one or more integuments
Palmate having lobes radiating from a common point -- used orig. only of 5-lobed leaves but now also of other lobed leaves, of leaf venation, and of other plant organs (as the tubers of some orchids)
Palmately compound
Palmately dissected
Palmately lobed
Palmately veined
Panicle a compound racemose inflorescence that is usu. a raceme in which the secondary branches are themselves racemose (as the inflorescence of yuccas) but sometimes merges into the cymose type (as in the horse chestnut)
Pappus the appendage or tuft of appendages crowning the ovary or fruit in various seed plants (as composites), being adapted for dispersal of the fruit by wind or other agencies, and consisting of all or part fo the perianth modified into bristles. scales, awns, or short teeth b : the group of bristles formed around the fruit by the calyx of members of the Dipsacaceae, Valerianaceae, and Calyceraceae Gk. pappos grandfather, old man, down of the chin
Parietal peripheral in location or orientation; esp : attached to the main wall rather than the axis or a cross wall of an ovary --used of an ovule or placenta
Parietal placentation
Pedicel one of the ultimate single flower-bearing divisions of a common peduncle (2) b a peduncle esp. if slender or delicate that bears a single flower
Peduncle a stalk that bears a flower or flower cluster -- see pedicel
Pellucid dot
Peltate having the stem or support attached to the lower surface instead of at the base or margin
Peltate scales
Peltate aromatic glands
Peltate scales
Pepo an indehiscent fleshy 1-celled or falsely three-celled many-seeded berry usu. with a hard rind (as a pumpkin, squash, melon, and cucumber) that is the characteristic fruit of the famiy Curcurbitaceae L. a melon
Perennial continuing or lasting for several years--used specif. of a plant (as delphinium) that dies back seasonally and produces new growth from a perennating part
Perfect with both male and female reproductive organs (stamens and pistils); bisexual (h)
Perianth the external envelope of a flower : floral leaves esp. when not differentiated into calyx and corolla
Perigynium the saclike bract that subtends the pistillate flower of sedges of the genus Carex and that in fruit becomes a flask-shaped envelope investing the achene
Petaloid resembling a flower petal in form, appearance, or texture
Petiole a slender stem that supports the blade of a foliage leaf and that is usu. cylindrical but sometimes flattened or even winged
Phyllary one of the involucral bracts subtending the flower head of a composite plant
Phyllode a flat expanded petiole that replaces the blade of a foliage leaf, fulfills the same functions, and is analogous to but not homologous with a cladophyll
Phytomelanin a papery "sooty" black layer over the seed of plants in the Asparagales, which includes agaves, aloes, onions and hyacinths. It is an important character for defining the group.(from UCMP Berkeley Glossary
Pinked with a saw-toothed edge ME pynken to make holes with a pointed instrument
Pinna a leaflet or primary division of a pinnate leaf or frond
Pinnate resembling a feather esp. in having similar parts arranged on opposite sides of an axis like the barbs on the rachis of a feather -- used esp. of compound leaves
Pinnately compound
Pinnately lobed (pinnatilobate) with pinnately arranged lobes (h)
Pinnate venation
Pistil the ovule-bearing organ of a seed plant : the ovary with its appendages (as style and stigma)
Pistillate flower
Pistillate inflorescence
Plumose feathery, plumelike
Pollen a mass of microspores in a seed plant appearing usu. as a fine dust made up of minute granular microspores typically formed in fours by reduction of a pollen mother cell with each grain consisting of a single cell that has a characteristicall sculptured outer wall and gives rise on germination to a pollen tube through which its male generative element passes to the ovule for fertilization of the egg
Pollinium (pl. Pollinia) the coherent mass of pollen grains that characterizes members of the Orchidaceae and Asclepiadaceae and often has a stalk bearing an adhesive disk that clings to visiting insects and facilitates withdrawal of the whole pollinium from its receptacle
Polyphyletic derived (as by convergence) from more than one ancestral line
Pome a fleshy accessory fruit (as of an apple) consisting of a central core with usu. five seeds enclosed within a bony or papery capsule made up of fused carpels and of an outer thickened fleshy layer made up of the much enlarged receptacle
Pore a minute opening esp. in an animal or plant by which matter passes through a membrane
Prickle a sharp pointed emergence arising from the epidermis or bark of a plant
Procumbent being or having stems that trail along the ground without putting forth roots
Prophyll a plant structure resembling a leaf (as a bracteole) or consisting of a modified or rudimentary leaf (as a foliar primordium)
Prostrate trailing on the ground : PROCUMBENT
Pulp the soft succulent part of fruit
Pulvinus a cushionlike enlargement of the base of a petiole or petiolule consiting of a mass of large thin-walled cells surrounding a vascular strand and functioning in turgor movements of leaves or leaflets by reversible volume changes in the cells
Raceme an inflorescence (as in the currant or lily-of-the-valley) in which the flowers are borne on stalks of about equal length along an elongated axis that continues to grow during flowering and open in succession from below -- compare cyme, corymb L. racemus: cluster of grapes or berries
Radiate head
Ray floret
Receptacle the end of the flower stalk on which the floral organs are borne and which is often somewhat enlarged (as in the composites) -- called also torus
Receptacular bract
Regular of a flower : having the members of each whorl symmetrical with respect to form : actinomorphic -- compare irregular
Resupinate inverted in position : appearing by a twist of the axis to be upside down or reversed
Ridges and grooves
Rosette a cluster of leaves developed in crowded circles or spirals from a crown or very short internode either basally (as in a dandelion) or at the apex (as in many tropical palms)
Rotate having the parts flat and spreading or radiating like the spokes of a wheel
Rust or rust disease : any of numerous destructive diseases of plants produced by fungi of the order Uredinales and characterized by reddish brown pustular lesions on stems, leaves, or other plant parts
Saccate having the form of a sac or pouch
Samara a dry indehiscent usu. one-seeded winged fruit (as of an ash or elm tree)
Sap the fluid part of a plant; specif : a watery solution of gases (as carbon dioxide), salts and other materials from the soil, and organic products of metabolism that circulate through the vascular system, carries raw materials to the periphera l chlorophyll-bearing cells, translocates the products of metabolism to other parts of the plant for use or storage and is a major commercial source of sugar in sugarcane, various palms, and the sugar maple
Saprophyte a plant living on dead or decaying organic matter
Scale one of the modified leaves serving in most seed plants to protect a bud before expansion . . . b : a thin membranous, chaffy or woody bract . . . d : the small appendage at the base of the petal in some plants of the family Caryophyllaceae e : one of the disklike trichomes making up the characteristic silvery or scurfy pubescence of the foliage in some plants (as Russian olive)
Scarious thin and membranous in texture
Scarious margined
Schizocarpic capsule
Scorpioid having a circinate arrangement of parts -- used chiefly of inflorescences
Scorpioid cyme
Seed the fertilized and ripened ovule of a seed plant comprising a miniature plant usu. accompanied by a supply of food (as endospernm or perisperm), enclosed in a protective seed coat, often accompanied by auxiliary structures (as an aril or caruncle), a nd capable under suitable conditions of independent development into a plant similar to the one that produced it -- see ENDOCARP
Seed coat the outer protective covering of a seed that is developed from one or more integuments often in combination with other adherent parts of the ovary (as in a caryopsis)
Sepal one of the modified leaves comprising a calyx -- compare PETAL
Sepaloid resembling or having the nature of a sepal
Septicidal dehiscent longitudinally at or along a septum -- compare LOCULICIDAL>
Septifragal breaking from the partitions -- used of dehiscence in which the valves of a capsule or pod break away from the dissepiments
Seta the slender stalk of the sporogonium of a bryophyte e : one of the stalked glands on plants of the genus Rubus f : the bristle in the utricle of some plants of the genus Carex NL, fr. L seta, saeta bristle
Sheath (1) : the lower part of a leaf (as of a grass) that more or less completely surrounds the stem (2) : an ensheathing spathe (3) ocrea
Sheathing base
Sheathing bract
Sheathing stipule
Short shoot
Single consisting of only one in number . . . b : having only the normal number of petals or rays : not double--used esp. of a horticultural plant
Sorus (pl. sori) a cluster of reproductive bodies or spores on a lower plant: as a : a clump of sporangia on a fertile frond of a fern
Spadix a fleshy or succulent spike that is usu. subtended by or enclosed in a leaflike spathe and is the inflorescence characteristic of the arums and palms
Spathe a sheathing bract or pair of bracts subtending or enclosing an inflorescence on the same axis exhibiting much variation in form and coloring, and occurring typically in plants whose inflorescence is a spadix or in modified form in many monocotyledonous plants (as the irises)
Spike an elongated indeterminate inflorescence similar to a raceme but having the flowers sessile on the main axis (as in common plantain) fr L. spica ; head (of grain), tuft (of a plant)
Spikelike cluster
Spiny leaf
Spiral band
Sporangium (pl. sporangia) A spore-bearing case or sac. Gr. sporos: a sowing 2. seedtime. II seed, produce, a crop.
Spore wall
Square stem
Stamen column
Staminate flower
Staminate inflorescence
Staminodium an abortive or sterile stamen (as in the flowers of the genus Parnassia)
Stem succulent
Stigma lobe
Stipular spines
Strobilus a conelike aggregation of sporophylls (as in the club mosses and horsetails) b : the cone of a gymnosperm
Style the usu. elongated portion of a pistil that connects the ovary with the stigma of a plant : a filiform prolongation of a plant ovary bearing a stigma at its apex
Style branch
Subtend to occupy an adjacent and usu. lower position to and often so as to embrace or enclose (a bract ~ing a flower)
Succulent having fleshy and juicy tissues
Superior a : situated above another organ: (1) of a calyx : attached to and apparently arising from the ovary (2 of an ovary : free from the calyx or other floral envelope
Superior carpel
Superior ovary
Swollen protuberant or abnormally distended
Swollen node
Synoecious with staminate and pistillate flowers together in the same head (h)
Tepal any of the modified leaves making up a perianth
Terete approximately cylindrical but usu. tapering at one or both ends
Terminal growing at the end of a branch or stem -- compare lateral
Thyrse an inflorescence as in the lilac and horse chestmut in which the main axis is racemose and the secondary and later axes are cymose
Thyrsoid having somewhat the form of a thyrse
Tracheid a long tubular cell that is peculiar to xylem, functions in conduction and support, and is characterized by tapering closed ends which are not absorbed as in tracheae and by thickened strongly lignified walls which commonly have bordered pits
Triangular appendage
Umbel a racemose inflorescence that is characteristic esp. of the family Umbelliferae and has the flower stalks in a cluster arising from a common point at the apex of the main stalk and reaching approximately the same height and sometimes branching again to form secondary clusters
Umbellate bearing, consisting of, or arranged in umbels   2 : resembling an umbel in form
United bract
Velamen (pl. velamina) the thick whitish or greenish multiseriate corky epidermis covering the aerial roots of an epiphytic orchid and consisting of compactly arranged nonliving cells capapble of absorbing water from the atmosphere
Vernation the arrangement of foliage leaves within the bud
Verticil a circle or whorl of similar body parts (as flowers about a point on an axis . . . )
Vessel a conducting tube in a vacscular plant formed in the xylem by the fusion and loss of end walls of a series of cells -- compare TRACHEID
Vestigial relating to or being a vestige, [being] a small and degenerate or imperfectly developed bodily part or organ that remains from one more fully developed in an earlier stage of the individual, in a past generation, or in closely related forms
Vestigial teeth
Weed an introduced plant growing in ground that is or has been in cultivation usu. to the detriment of the crop or to the disfigurement of the place : an economically useless plant : a plant of unsightly appearance esp : one of wild or rank growth
Whorled an arrangement of two or more anatomical parts or organs of one kind in a circle around the same point on an axis
Woody cupule
Xerophyte a plant structually adapted for life nd growth with with a limited water supply esp. by means of mechanisms (as epidermal thickening , waxy or resinous coats, or dense pubescence) that limit transpiration or that provide for the storabe of water -- u sed both of desert plants and of those occupying environments (as salt marshes or acid bogs) where water absorption is impeded by excess salts or acids in solution; compare HYDROPHYTE, MESOPHYTE
Zygomorphic bilaterally symetrical specif : capable of division into esentially symmetrical halves by only one longitudinal plane passing through the axis -- compare actinomorphic

See also the Classified Glossary from Vascular Plant Systematics
(Radford, A. E., W. C. Dickison, J. R. Massey, C. R. Bell. 1976. Harper and Row, New York.)

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