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Perennial suffrutescent herbs or shrubs. Stems terete to quadrangular, glabrous to pubescent, soft-wooded, nodes frequently swollen. Leaves opposite, petiolate; blades usually large, oblong to elliptic, membranous to coriaceous, marginally toothed, lobed, crenate, undulate or entire. Inflorescences of terminal or axillary spikes, solitary to few, often conspicuous with showy bracts and flowers; bracts usually imbricate, brightly colored or green, marginally toothed or entire, sometimes bearing dorsal clusters of submarginal glands; bracteoles 2, laterally subtending calyx, usually subfalcate. Flowers nearly regular to strongly bilipped, homostylous; calyx 5-lobed, lobes subequal, lanceolate, posterior (adaxial) lobe, anterior (abaxial) pair, and lateral pair of unequal width; corolla straight or curved, limb usually bilipped, pale to bright red, crimson, scarlet or orange, upper lip (posterior) erect, 2-lobed (lobes sometimes partially or completely united), lower lip (anterior) reflexed or spreading, 3-lobed, lobes subequal to strongly dimorphic with lateral ones reduced to essentially lacking; stamens 4, usually exserted but rarely if ever exceeding upper corolla lip, anthers narrow, 1-thecous, often dorsally pilose and adhering at apices by intertwining trichomes; pollen usually ellipsoidal, 3-aperturate, with exine sculpturing usually reticulate to occasionally verrucose or psilate; staminode usually none, if present, consisting of slender short filament or small callous region; ovary with 2 ovules per locule, style, frequently extending through and slightly exceeding the posterior pair of anthers. Capsules clavate to subglobose, explosively dehiscent on drying; seeds 4, brown, rounded to somewhat angled and strongly flattened to subglobose, each supported by a curved retinaculum.


Andes present, E Brazil present, Guianas present, NW Mexico present, Southern America: Brazil South (Santa Catarina present); Colombia (Colombia present); Ecuador (Ecuador present); Peru (Peru present)
A neotropical genus of about 175 species extending from NW Mexico southeastward in dry forests to SE Brazil (Santa Catarina); the greatest concentration of species occurs in the Andes of Colombia, Ecuador and Peru; 3 species in the Guianas.


A. pulcherrima, A. scabra.


Growth rings present due to a narrow zone of thicker walled fibres with a narrow lumen.
Vessels diffuse with a faint tendency to radial arrangement, about 30% solitary, remainder in radial multiples of 2-6 and in clusters, over 100 sq. mm, outline round to elliptic, 25-50 µm wide. Vessel member length 500 (250-730) µm. Perforations simple, intervascular pits 3-5 µm, slits enclosed; vessel/ray pitting identical.
Rays 1-2-seriate, 6 (4-10) per mm. Heterogeneous, all cell types present, but mostly square and upright. Biseriates often with very high margins of square and upright cells. Vertically fused rays present, up to 1200 µm high. Contents not noticed.
Parenchyma very scarce, restricted to a few strands bordering a vessel. Strands of 2-3 cells.
Ground tissue consisting of generally non-septate fibres, septates very scarce. Diameter angular, 15-20 µm, walls 5-7.5 µm thick. Pits minute, simple, mainly in radial walls. Length 880 (730-1110) µm. F/V ratio: 1.76.