Raphanus L.

Scientific Description

Common name. Radish. Family Brassicaceae.

Habit and leaf form. Herbs. Annual, or biennial, or perennial. Leaves cauline, or basal and cauline. Plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves. Stem internodes solid. To 0.15–1(–1.5) m high. Mesophytic. Leaves medium-sized to large; alternate; spiral; ‘herbaceous’; petiolate (lower leaves), or subsessile to sessile; non-sheathing; simple; epulvinate. Leaf blades dissected to entire; lyrate palmately lobed (the upper leaves reducing); pinnately veined; cross-venulate. Leaves without stipules. Leaf blade margins entire, or serrate, or dentate. Leaves without a persistent basal meristem. Leaf anatomy. Hairs present, or absent; glandular hairs absent; complex hairs absent. Branched hairs absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in racemes, or in corymbs, or in panicles. The terminal inflorescence unit racemose. Flowers pedicellate; ebracteate; ebracteolate; small to medium-sized; regular; 2 merous; cyclic. Floral receptacle with neither androphore nor gynophore. Free hypanthium absent. Hypogynous disk present; of separate members. Nectariferous glands 4. Perianth with distinct calyx and corolla; 8; 3 -whorled (K 2+2, C 4). Calyx present; 4; erect; 2 -whorled; polysepalous; usually erect; decussate; regular. Sepals lateral sepals slightly saccate. Corolla present; 4; 1 -whorled; alternating with the calyx; polypetalous; imbricate, or contorted; regular; with contrasting markings (darker veins), or plain; white, or yellow, or purple. Petals clawed. Androecial members definite in number. Androecium 6. Androecial members branched (in that the inner whorl of 4 is derived from only 2 primordia); free of the perianth; markedly unequal; free of one another; 2 -whorled (2+4). Androecium exclusively of fertile stamens. Stamens 6; tetradynamous; all more or less similar in shape; hypogynous, on receptacle, outer stamens lateral. Filaments not appendiculate. Anthers basifixed; non-versatile; dehiscing via longitudinal slits; introrse; unilocular to bilocular; tetrasporangiate; appendaged, or unappendaged. Pollen shed as single grains. Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary plurilocular; 2 locular. Locules secondarily divided by ‘false septa’. Gynoecium transverse. Ovary sessile. Gynoecium stylate. Styles 1; apical. Stigmas 1; commissural; 1–2 - lobed (and capitate); capitate. Placentation parietal. Ovules (1–)3–50 per locule; with ventral raphe; non-arillate; anatropous.

Fruit and seed features. Fruit 15–90 mm long; non-fleshy; indehiscent, or lomentaceous (then breaking into 1-seeded units); a siliqua; 2 celled; 1–12 seeded. Seed rows per locule 1. Seeds scantily endospermic, or non-endospermic; not mucous; small to medium sized; wingless (spherical or ovoid). Embryo well differentiated. Cotyledons 2; folded; incumbent; conduplicate. Embryo bent.

Physiology, biochemistry. Mustard-oils present.

Special features. Fruit body distinctly differentiated into valve and beak regions. Beak seedless. Replum present and complete. Fruit terete. The inner (lateral) pair of sepals somewhat saccate basally for nectar storage, or not noticeably saccate. Petals not peculiarly elongated as in Stenopetalum. Nectariferous glands lateral and median. Siliquae moniliform, or not moniliform.

Etymology. From the Latin raphanus (radish).