Isoglossa ciliata (Nees) Engl.

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

Morphology General Habit

Perennial herb or subshrub, 30–160 cm tall, often straggling.

Morphology Stem

Stems retrorse-pubescent in two opposite furrows, with scattered crisped hairs elsewhere.

Morphology Leaves

Leaves sometimes immature at flowering, ovate or elliptic, 3.5–9.5 × 2–4.5 cm, base attenuate, apex acute to acuminate, sparsely antrorse-pubescent mainly on midrib, main veins and margin; lateral veins 4–6 pairs; petiole 10–44 mm long.

Morphology Reproductive morphology Inflorescences

Inflorescences terminal and axillary, fasciculate or shortly spiciform, 1–3 cm long, partially or wholly 1-sided, each fertile cymule single-flowered, sessile; bracts lanceolate, narrowly pandurate or oblanceolate, 7–11.5 × 1.5–4 mm, apex acuminate or spathulate, surface green with a narrow or (in our region) rather broad pale-hyaline margin in lower half, surface appressed-pubescent, margin densely pale-ciliate particularly on hyaline portion, sometimes also with short spreading glandular hairs; bracteoles lanceolate, 5.5–9.5 × 1.5–3 mm, hyaline margin ± broad.

Morphology Reproductive morphology Flowers Calyx

Calyx lobes linear-lanceolate, 4–7 mm long in flower and fruit, margin densely ciliate, glandular hairs usually absent.

Morphology Reproductive morphology Flowers Corolla

Corolla 12.5–14 mm long, white to mauve, often with red or purple markings on palate and/or throat; limb sparsely pubescent externally or glabrous except for a few hairs at lobe apex; tube 5–6 mm long, somewhat widened upwards, with an interrupted ring of hairs within around attachment point of stamens; upper lip hooded, 7–10 mm long, lobes to 1 mm; lower lip 7–8.5 mm long, lobes rounded, to 1 mm, palate upraised and with prominent herring-bone patterning.

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens attached in upper half of corolla tube; filaments free for 4–5.5 mm; anther thecae superposed, held almost patent to filament or lower theca less strongly oblique, each 1–1.7 mm long.

Morphology Reproductive morphology Fruits

Capsule 5–8 mm long, glabrous, only 1–2 seeds maturing.

Morphology Reproductive morphology Seeds

Seeds 2.2–2.8 ×1.5–2.5 mm, rugose, rather smooth at maturity.

Distribution

Also in South Africa (E & W Cape, KwaZulu-Natal) and Swaziland.

Ecology

In lowland forest understorey, often along forest margins or in clearings. Van Steenis (Bothalia 12: 553, 1978) records this as a periodic mass-flowering, monocarpic species with a c.10 year cycle; c.20 m.

Conservation

Conservation notes: Known only from a single collection in our region but locally abundant in the coastal forests of KwaZulu-Natal and the Cape, particularly favouring open forest and forest margins; Least Concern.