Ageratinastrum palustre Wild & G.V.Pope

Compositae, G. V. Pope. Flora Zambesiaca 6:1. 1992

Morphology General Habit

An erect stiff perennial herb to c. 1 m. tall, with annual stems from a woody rootstock.

Morphology Stem

Stems many, strict, branching above, densely leafy with internodes less than 2 cm. long, whitish pilose-pubescent, glabrescent below; indumentum of short-stalked flagelliform hairs.

Morphology Leaves

Leaves alternate or spirally arranged sometimes opposite or whorled, subsessile or with petioles to c. 2 mm. long; lamina 1–3.3 x 0.4–1.2 cm., narrowly oblong-lanceolate to narrowly ovate, acute mucronulate at the apex, cuneate to rounded below, margins ± revolute, upper surface glabrous or thinly sparsely pilose-puberulous with nerves ± impressed, the lower surface paler and sparsely pilose especially on the nerves, glandular-punctate.

Morphology Reproductive morphology Inflorescences Capitulum

Capitula numerous, singly or in 2–10-capitulate clusters at the ends of branches, or capitulum-clusters ± corymbiformly cymose at the stem apex.

Morphology Reproductive morphology Inflorescences Bracts Involucre

Involucres 3–4 x 3–4.5 mm., campanulate to subglobose; florets exserted.

Morphology Reproductive morphology Inflorescences Bracts Phyllaries

Phyllaries several-seriate, purple and acute above, tomentellous to woolly outside; the outer phyllaries from c. 1 mm. long, ovate; the inner to c. 4 mm. long, narrowly oblong-lanceolate.

Morphology Reproductive morphology Flowers Receptacle

Receptacle shallowly alveolate.

Morphology Reproductive morphology Flowers Corolla

Corollas mauve, darker in the upper half, 5–6 mm. long, narrowly funnel-shaped, puberulous or thinly pilose outside at least on the lobes, glandular, the lobes purple-tipped.

Morphology Reproductive morphology Fruits

Achenes 1–1.5 mm. long, turbinate, truncate at the apex, 4–5-sided with obscure narrow ribs on the angles, rugose or transversely ridged on the faces between the ribs, glabrous or sparsely setulose, minutely brown gland-dotted; pappus of broad ± united shiny, white brownish or sometimes purplish scales, 0.5–1 mm. long and ± lacerate on the upper margin, occasionally scales ± free and alternating with 1–3 narrow paleaceous setae which ± exceed the scales in length.