Buchnera

Annual or perennial, often hemiparasitic herbs, usually somewhat rigid and scabrid, turning dark on drying; stems erect, ascending or prostrate, simple or branched, glabrous to hispid-scabrid. Leaves usually opposite or quasiverticillate, sometimes subopposite or alternate above, sessile to shortly petiolate, 1-5-veined, lowest ones usually obovate, entire or dentate, upper ones narrow, entire or denticulate, gradually passing into bracts. Flowers often small, sessile or subsessile in axils of upper leaves or bracts, usually bibracteolate, solitary, in terminal, compact to lax spikes or in terminal, or axillary, +/- globose clusters; inflorescences often lengthen in fruit. Calyx tubular, 4- or 5-toothed, tube cylindrical, narrow, 5- or 10(7 or 8)-veined or -ribbed; teeth short, deltoid to lanceolate-acuminate, usually scabrid on margin. Corolla tubular, 4- or 5(6)-lobed, slightly irregular; tube slender cylindrical, longer than calyx, straight or gently curved, glabrous to softly pilose, throat sometimes densely pilose; limb shorter than tube, spreading; lobes subequal, obovate to subcircular or oblong, entire or emarginate, 2 posterior ones often a little smaller, interior in bud. Stamens 4, slightly didynamous, subequal, arising about middle of corolla tube, subsessile or with short filaments, included; anthers unithecate, erect, dorsifixed, acute, blunt at base. Ovary bilocular, elliptical; ovules many per locule; style terete, straight; stigma thickened or clavate, entire or emarginate, almost as long as style, included. Fruit an ovoid to oblong, loculicidal capsule. Seeds many, obovoid or oblong; testa membranous, reticulate, tightly investing endosperm. x = 10 (polyploidy).