Plagiobothrys Fisch. & C.A.Mey.
Index Seminum [St.Petersburg (Petropolitanus)] p46 (1836)

Name Status: Current
Browse to the list of specimens for Plagiobothrys Fisch. & C.A.Mey.

Scientific Description
H.R. Coleman, Thursday 8 September 2016

Family Boraginaceae.

Habit and leaf form. Herbs; without essential oils. Autotrophic. Annual. Leaves basal and cauline. Plants with a basal concentration of leaves. Helophytic, or mesophytic, or xerophytic. Leaves small to medium-sized; alternate and opposite (opposite in basal rosette); petiolate to sessile; sheathing (in basal rosette), or non-sheathing (above); not gland-dotted; simple; epulvinate. Leaf blades dorsiventral, or isobilateral; entire; flat; linear to lanceolate; linear, or obovate, or triangular; cross-venulate. Mature leaf blades adaxially glabrous, or pubescent; abaxially glabrous, or pubescent. Leaves without stipules. Leaf blade margins entire. Leaves without a persistent basal meristem. Leaf anatomy. Hairs present (sometimes with a broad base), or absent. Urticating hairs absent. Stem anatomy. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries absent (from ovary). Entomophilous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in cymes. Inflorescences simple, or compound. The terminal inflorescence unit cymose (coiled at first). Inflorescences terminal; of scorpioid cymes with widely spaced flowers; not pseudanthial. Flowers pedicellate to subsessile; bracteate; bracteolate; minute to small; regular; 5 merous (or anisomerous, with supernumerary K); cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present, or absent. Perianth with distinct calyx and corolla; 10–13; 2 -whorled; isomerous, or anisomerous. Calyx present; 5, or 5–8; 1 -whorled; gamosepalous; lobed. Calyx lobes about the same length as the tube, or markedly longer than the tube. Calyx imbricate, or open in bud, or valvate. Degree of gamosepaly, maximum length joined/total calyx length 0.25–0.5. Calyx regular, or regular to unequal but not bilabiate (when fruiting); neither appendaged nor spurred; persistent; accrescent. Calyx lobes ovate, or linear. Corolla present; 5; 1 -whorled; not appendiculate; gamopetalous; lobed. Corolla lobes markedly shorter than the tube. Corolla imbricate, or contorted; tubular; regular; glabrous abaxially; glabrous adaxially; plain; white. Corolla lobes oblong (to almost square). Androecial members definite in number. Androecium 5. Androecial members unbranched; adnate (to the corolla); all equal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5. Staminal insertion midway down the corolla tube. Stamens all inserted at the same level; remaining included; isomerous with the perianth; oppositisepalous; filantherous (to subsessile). Anthers dorsifixed to basifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate; unappendaged (although constricted at apex). Gynoecium 2 carpelled. The pistil 4 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; eu-syncarpous; superior. Ovary plurilocular (deeply 2–4-lobed); 2 locular (‘really’, but rarely ostensibly so), or 4 locular (ostensibly, via false septa). Locules secondarily divided by ‘false septa’. Gynoecium median; stylate. Styles 1; simple; from a depression at the top of the ovary; ‘gynobasic’. Stigmas 1; 1 - lobed; capitate. Placentation axile to basal. Ovules differentiated; 2 per locule (i.e. per true locule), or 1 per locule (per cell, the gynoecium separating into one-ovuled portions); horizontal to ascending; epitropous; non-arillate; anatropous, or hemianatropous.

Fruit and seed features. Fruit aerial; non-fleshy; not hairy; not spinose; a schizocarp. Mericarps 2–4; comprising achenes, or comprising nutlets, or comprising drupelets; shiny, or dull. Seeds endospermic, or non-endospermic. Cotyledons 2. Embryo straight, or curved.

Special features. Corolla tube straight.

Etymology. From the Greek for "placed sideways, oblique" and "pit"; refers to the scar, off centre on the nutlets.

Taxonomic Literature

  • Blackall, William E.; Grieve, Brian J. (1981). How to know Western Australian wildflowers : a key to the flora of the extratropical regions of Western Australia. Part IIIB, (Epacridaceae-Lamiaceae). University of W.A. Press. Perth.