Scaevola L.

Scientific Description

Common name. Fanflowers. Family Goodeniaceae.

Habit and leaf form. Trees (small), or shrubs, or herbs (or scrambler). ‘Normal’ plants, or switch-plants; sometimes with the principal photosynthesizing function transferred to stems. Leaves well developed, or much reduced. Plants unarmed, or spiny (rarely). Perennial. Leaves basal and cauline (mostly cauline). Plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves. Stem internodes solid (ass.). Mesophytic, or xerophytic. Leaves alternate, or opposite, or whorled (rarely); spiral; petiolate, or subsessile, or sessile; non-sheathing; simple; epulvinate. Leaf blades dissected, or entire; linear, or ovate, or obovate, or oblong, or elliptic, or orbicular; when dissected, pinnatifid; pinnately veined. Leaves without stipules. Leaf blade margins entire, or serrate, or dentate. Leaves without a persistent basal meristem. Leaf anatomy. Hairs present; glandular hairs present; complex hairs present, or absent. Extra-floral nectaries absent (ass.). Stem anatomy. Secondary thickening absent, or developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous. Pollination mechanism conspicuously specialized (involving a stylar modification for pollen presentation).

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; terminal, or axillary; in cymes (in thyrses), or in racemes, or in spikes. The terminal inflorescence unit cymose, or racemose. Inflorescences terminal, or axillary. Flowers pedicellate to sessile; bracteate (opposite, leaf-like); bracteolate (small, inserted just below calyx); small to medium-sized; very irregular. The floral asymmetry involving the perianth and involving the androecium. Flowers 5 merous; cyclic; tetracyclic. Free hypanthium absent. Perianth with distinct calyx and corolla; (8–)10; 2 -whorled; isomerous, or anisomerous. Calyx present; 5 (often small and sometimes reduced to an undulate rim); 1 -whorled; gamosepalous; blunt-lobed; tubular. Corolla present; 5 (more or less equal); 1 -whorled; not appendiculate; gamopetalous; lobed. Corolla tube adaxially deeply split. Corolla valvate; tubular; unequal but not bilabiate (usually, the lobes digitately arranged), or bilabiate (the upper lobes sometimes shorter); hairy adaxially; white, or yellow (rarely, then a scrambling shrub), or pink, or purple (or mauve); not spurred. Androecial members definite in number. Androecium 5. Androecial members free of the perianth, or adnate; all equal (ass.); free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; all more or less similar in shape (ass.); isomerous with the perianth; oppositisepalous (at the base of the corolla); all alternating with the corolla members. Anthers separate from one another; basifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate. Pollen shed in aggregates, or shed as single grains. Gynoecium 2 carpelled. The pistil 1–2(–4) celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; inferior. Ovary unilocular, or plurilocular; 1–2(–4) locular. Locules secondarily divided by ‘false septa’, or without ‘false septa’. Gynoecium stylate. Styles 1; bearing an ‘indusium’ beneath the stigma. Indusium cupular. Styles apical. Stigmas 1; 2 - lobed. Placentation axile. Ovules in the single cavity 1–2; 1–2 per locule; ascending; non-arillate; anatropous.

Fruit and seed features. Fruit fleshy, or non-fleshy; indehiscent; a drupe, or a nut; 1 seeded (per cell, usually). Seeds copiously endospermic. Endosperm oily. Seeds not compressed (cylindric); winged, or wingless. Cotyledons 2. Embryo straight.

Special features. The upper lip of the corolla if seen as such, incorporating 2 members, the lower 3, or suppressed, the lower incorporating all five members.

Etymology. From the Latin Scaevola, a Roman surname; from the Latin for "left-handed"; originating from C. Mucius Scaevola (507 BC) who attempted to assassinate Porsena and, on being apprehended, burned off his right hand; refers to the one-sided fan-shaped corolla of many species.