- Caducous. Dropping off very early, usually applied to floral parts
- Calcarate. Spurred
- Calceolate. Slipper-shaped, as in the corolla of Cypripedium
- Callosity. A thickened, raised area, which is usually hard; a callus
- Calybium. A hard one-loculed dry fruit derived from an inferior ovary, as in Quercus
- Calyx. The lowermost whorl of modified leaves, sepals
- Campanulate. Bell-shaped; with flaring tube about as broad as long and a flaring limb
- Campylodromous. With several primary veins or their branches diverging at or close to a single point and running in strongly developed, basally recurved arches which converge toward the apex, reaching it or not
- Campylotropous. With body bent or curved on one side so that micropyle is near medially attached funiculus
- Canaliculate. Longitudinally grooved, usually in relation to petioles or midribs
- Cancellate or Clathrate. Latticed
- Canescent or Incanous. Covered with dense, fine grayish-white trichomes
- Cantharophily. Pollinated by beetles
- Capillate. Hair-shaped
- Capitate. Head-like
- Capitulum or Head. A determinate or indeterminate crowded group of sessile or subsessile flowers on a compound receptacle or torus
- Dry, dehiscent fruit derived from a compound ovary of 2 or more carpels. Capsule, Indehiscent - Dry fruit derived from a two- or more loculed ovary, as in Peplis
- Carina. Keel. Carinal Canal - A canal beneath a stem ridge associated with a vascular bundle
- Carinate. Keeled
- Carnose or Sarcous. Fleshy
- Carpel. The female sporophyll within flower; floral organ that bears ovules in angiosperms; unit of compound pistil
- Carpophore. Floral axis extension between adjacent carpels, as in the Apiaceae
- Carpopodium. Short, thick, pistillate stalk
- Carpotaxis. Arrangement of fruits, reproductive in function
- Cartilaginous. Hard and tough but flexible
- Carunculate. With an excrescent outgrowth from integuments near the hilum, as in Euphorbia; fibrous with stringy or cord-like seed coat, as mace in Myristica
- Caryopsis or Grain. A one-seeded dry, indehiscent fruit with the seed coat adnate to the fruit wall, derived from a one-loculed superior ovary
- Catadromous. Having the first lobe or segment of a pinna arising acroscopically in compound leaves
- Cataphyll. Rudimentary scale leaf produced by seedling, usually in cryptocotylar species
- Caudate (Base attenuate). Acuminate with concave margins
- Caudex. A short, thick, vertical or branched perennial stem usually subterranean, or at ground level
- Cauline. May be all over (general) or along the ribs (costal), or in the grooves (canaliculate)
- Caulocarpic. Plants having the stem living for many years, bearing flowers and fruits
- Caulous. With branches more or less evenly spaced along trunk
- Central Canal. The large centrally located air space in the stem
- Centrifugal. Developing from the inside outward, or from top downward
- Centripetal. Developing from the outside inward, or from bottom upward
- Centroramous. At the center of the branch
- Ceraceous. Waxy
- Cernuous. Drooping
- Cespitose. Short, much-branched, plant forming a cushion
- Chaff or Pale. Scale or bract at base of tubular flower in composites
- Chalaza. End of ovule opposite micropyle
- Chalazogamy. Pollen tube entrance through chalaza
- Channelled or Canaliculate. With a longitudinal groove
- Chartaceous. Papery, opaque and thin
- Chasmantheric Pollination. Pollen transferred from a normally dehisced anther by a pollinating agent with pollen grain germination on the stigma and subsequent growth of the pollen tube through stigma, style and the ovule into the embryo sac
- Cheiropterophily. Pollinated by bats
- Chlamydeous. With perianth
- Ciliate. With conspicuous marginal trichomes
- Ciliolate. With tiny or small marginal trichomes
- Cincinnus. A tight, modified helicoid cyme in which pedicels are short on the developed side
- Circinate. With lamina rolled from apex to base with apex in center of coil
- Circumalate. Winged circumferentially
- Circumferential. At or near the circumference; surrounding a rounded structure
- Circumscissle Capsule or Pyxis. One that dehisces circumferentially, as in Plantago
- Cirrhous. More than 10:1 l/w, coiled and flexuous
- Cladode (phylloclad). A flattened main stem resembling a leaf
- Cladodromous. With a single primary vein, the secondary veins not terminating at the margin and freely ramified toward it
- Cladoptosic. Shedding of branches, stems and leaves simultaneously, as in Taxodium
- Clambering. Sprawling across objects, without climbing structures
- Clasping. Partly surrounding the stem.
- Clavate. Club-shaped
- Claw. The long, narrow petiole-like base of a sepal or petal
- Cleft. Indentations or incisions cut 1/4-1/2 distance to midrib or midvein
- Cleistantheric Pollination. Pollen not transferred from a normally dehisced anther by a pollinating agent; pollen grain germinates within the anther with subsequent growth of the pollen tube through the anther wall and ovary wall into the ovule and embryo sac
- Climbing. Growing upward by means of tendrils, petioles, or adventitious roots
- Clinanthium. The compound receptacle of the composite head
- Clouded. Colors are unequally blended together
- Clustered, Conglomerate, Agglomerate, Crowded, Aggregate. Parts dense, usually irregularly overlapping each other
- Coalescent. With like or unlike parts or organs incompletely separated; partially fused in a more or less irregular fashion
- Cochleate. Snail-shaped
- Coenocarpium (Various Structures). Multiple fruit derived from ovaries, floral parts, and receptacles of many coalesced flowers, as in Ananas
- Coetaneous. Flowering as the leaves expand; synantherous
- Coherent. With like parts or organs joined, but only superficially and without actual histological continuity
- Coleoptile. Protective sheath around epicotyl in grasses
- Coleorhiza. Protective sheath around radicle in grasses
- Collet. External demarcation between hypocotyl and root
- Columella. The sterile central part within a mature sporangium or capsule
- Column, Gynostemium or Gynandrium. With fused stamens and carpels (stigma and style) as in Orchis
- Columnar. Erect with a stout main stem or trunk
- Comose. With a tuft of trichomes, usually apical
- Complete. Leaf with blade, petiole, and stipules; flower with four types of floral parts
- Compound. Composed of two or more anatomically or morphologically equivalent units, whether subdivided into them or an aggregate of them
- Compressed or Complanate. Flattened
- Conduplicate. Longitudinally folded upward or downward along the central axis so that ventral and/or dorsal sides face each other
- Cone (strobilus). Aggregation of sporangia-bearing structures at tip of the stem (either sporophylls or scales in the Gymnosperms)
- Conical. Having figure of true cone
- Conjugate. Fused pairs, as the fruits of Lonicera
- Connate. With like parts or organs integrally fused to one another with histological continuity
- Connective. Filament extension between thecae
- Connivent. Convergent apically without fusion
- Contiguous. Touching but not adnate, connate, adherent, or coherent
- Continuous. Symmetry of arrangement even, not broken
- Contorted. Twisted around a central axis; twisted
- Contortuplicate. With weirdly folded corrugate cotyledons
- Contractile or Pull. Roots capable of shortening, usually drawing the plant or plant part deeper into the soil, usually with a wrinkled surface
- Convolute. With one lamina enrolled in another lamina
- Cordate (Apex obcordate). Lobe rounded; sinus depth 1/8-1/4 distance to midpoint of blade; margins convex and/or straight
- Cordiform. Heart-shaped
- Coriaceous. Thick and leathery
- Corm. The enlarged, solid, fleshy base of a stem with scales; an upright underground storage stem
- Cormel. Small corm produced at base of parent corm
- Corneous. Horny
- Corniculate. Horned
- Corolla. The whorl of petals located above the sepals
- Corona. A crown; any outgrowth between the stamens and corolla which may be petaline or staminal in origin
- Coronate. Tubular or flaring perianth or staminal outgrowth; petaloid appendage
- Coroniform. Crown-shaped
- Corrugate. With lamina irregularly folded in all directions, wrinkled
- Corymb. A flat-topped or convex indeterminate cluster of flowers. Compound Corymb - A branched corymb
- Costa. The midvein of a minor divsion of a fern leaf
- Costate. Coarsely ribbed
- Cotyledon. Embryonic leaf or leaves in seed
- Cotylespermous. With food reserve in cotyledon, derived from zygote
- Cotyliform. Cup-shaped
- Craspedodromous. Simple - With a single primary vein, all of the secondary veins and their branches terminating at the margin. Mixed - With a single primary vein, some of the secondary veins terminating at the margin and an approximately equal number otherwise
- Crateriform. Shallow cup-shaped as the involucre of some species of Quercus
- Crenate. Shallowly ascending round-toothed, or teeth obtuse; teeth cut less than 1/8 way to midrib or midvein
- Crenulate. Diminutive of crenate, teeth cut to 1/16 distance to midrib or midvein
- Crested or Cristate. With a terminal ridge or tuft
- Crispate. Curled; margins divided and twisted in more than one plane
- Crozier. The coiled developing leaf of a fern
- Cruciform or Cruciate. Cross-shaped
- Crustaceous. Hard, thin, and brittle
- Cryptantherous. With stamens included
- Cryptocotylar or Hypogeous. With the cotyledons remaining inside the seed; seed usually remaining below ground
- Cucullate. Hooded
- Culm. Flowering and fruiting stems of grasses and sedges
- Cupule. Fused involucral bracts subtending flower, as in Quercus
- Curvative or arcuate. With lamina folded transversely into an arc
- Cuspidate. Acute but coriaceous and stiff
- Cyathium. A pseudanthium subtended by an involucre, frequently with petaloid glands, as in Euphorbia
- Cylindric. Long-tubular
- Cymbiform. Boat-shaped
- Cyme or Dichasium. A determinate, dichotomous inflorescence with the pedicels of equal length. Scorpioid Cyme or Rhipidium - A zigzag determinate inflorescence with branches developed on opposite sides of the rachis alternately. Compound Cyme - A branched cyme
- Cymule. A simple, small dichasium
- Cypsela. An achene derived from a one-loculed, inferior ovary