Whitfieldiinae

Manzitto-Tripp, Erin A., Darbyshire, Iain, Daniel, Lucinda A. McDade Thomas F. & Kiel, Carrie A., 2022, Revised classification of Acanthaceae and worldwide dichotomous keys, TAXON 71 (1), pp. 103-153 : 140-141

Whitfieldiinae I.Darbysh. & E.Tripp, subtr. nov.

– Type: Whitfieldia Hook.

Perennial herbs or shrubs with cystoliths; leaves opposite; inflorescences variously spiciform or racemoid thyrses, sometimes compounded into a panicle, or fasciculate, glomerulate or shortly umbellate; individual flowers or floral units subtended by paired bracts (or bracteoles), these often conspicuous, clasping and sometimes partially connate at least in bud; calyces equally to somewhat unequally 5-lobed; corolla ranging from subactinomorphic to bilabiate, with traces trifurcating in the lobes, filament curtain absent, aestivation left-contort (also reported as ascending-cochlear but this not observed by the current authors); androecium of 4 stamens (rarely reduced to 2 stamens plus 2 staminodes in some flowers), with or without an additional staminode, anthers bithecous, thecae inserted equally on the filament and held at an equal height; stigma capitate, the lobes symmetrical; capsule 2- to 4-seeded, seeds (where known) with concentric rings of coarse scales at least towards margin, surfaces lacking trichomes; pollen lenticular, 2-pororate, with a pronounced marginal girdle (this typically psilate), or rarely globose and pantoforate, areas around the pores granular or micro-echinate.

Note. – If Ritonia Benoist proves to be a member of Whitfieldiinae, then the description of the androecium must be modified to include 2 stamens plus 2 staminodes as a nonaberrant trait.