Isoglossa pawekiae Brummitt & Feika

Flora Zambesiaca Acanthaceae (part 2) by Iain Darbyshire, Kaj Vollesen and Ensermu Kelbessa

Morphology General Habit

Shrub to 150–300 cm tall.

Morphology Stem

Young stems shortly crisped-pubescent on two opposite sides, hairs mainly antrorse; mature stems woody, glabrescent.

Morphology Leaves

Leaves (oblong-)elliptic or somewhat obovate, 10–18.5 × 4–6.3 cm, base of lower leaves long-attenuate, forming a narrow wing along midrib then abruptly truncate, apex acute to acuminate, upper surface glabrous or sparsely pubescent, principal veins beneath and margin shortly antrorse-pubescent; lateral veins 6–10 pairs, these and scalariform tertiary veins ± prominent beneath; petiole 0–2 mm long.

Morphology Reproductive morphology Inflorescences

Inflorescence terminal and often also in upper axils, narrowly spiciform, to 9–15.5 cm long, each cymule single-flowered, flowers sessile; axis pale crisped- and/or appressed-puberulous; bracts and bracteoles subequal, triangular to narrowly so, 2.5–6 × 1.5–3 mm, apex acute or attenuate, surface pale appressed-puberulous, margin pale-ciliate.

Morphology Reproductive morphology Flowers Calyx

Calyx tube 2–2.5 mm long, lobes lanceolate, 5–9 mm long in flower and fruit, imbricate towards base, margins narrowly hyaline, apex acute to acuminate, indumentum as bracts.

Morphology Reproductive morphology Flowers Corolla

Corolla 38–50 mm long, white, pale pink or pale purple; crisped-puberulous externally; tube 30–34 mm long, basal c.7 mm cylindrical, then broadly expanded into throat with an interrupted ring of hairs within c.8 mm from base; upper lip broadly triangular, 14–15.5 mm long, lobes 3–3.5 mm; lower lip 15–16.5 mm long, lobes 3.5–4.5 mm, palate upraised with faint herring-bone patterning.

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens attached c.14 mm from corolla base; filaments free for 12.5–14 mm; anther thecae parallel and held at subequal height, 3.2–4 mm long.

Morphology Reproductive morphology Fruits

Capsule 21–22 mm long, glabrous.

Morphology Reproductive morphology Seeds

Immature seeds only seen, rugose and with numerous minute processes.

Distribution

Not known elsewhere.

Ecology

Riverine thickets, termitaria in Brachystegia woodland, sometimes forming large colonies; 1000–1600 m.

Conservation

Conservation notes: An extremely local species, apparently restricted to three river systems in the Misuku area of Malawi where it can be locally abundant; possibly threatened globally.