毛叶束尾草 mao ye shu wei cao

Phacelurus latifolius (Steudel) Ohwi var. trichophyllus (S. L. Zhong) B. S. Sun & Z. H. Hu; Rhytachne anisonodis B. S. Sun; R. lijiangensis B. S. Sun.

Perennial, shortly rhizomatous. Culms erect, 1–2 m tall, 3–4 mm in diam., many-noded, branching in upper part. Leaf sheaths hispid with short, tubercle-based hairs or glabrous, usually longer than internodes; leaf blades lanceolate, papery, 10–20 × 1–2.5 cm, sparsely hispid with short, scattered, tubercle-based hairs, base rounded, margins serrulate, apex acuminate; ligule 0.5–1 mm. Inflorescence of 1–6 subdigitate racemes. Racemes up to 15 cm or more, stiffly suberect, spikelets normally paired, occasionally triads of 2 sessile and 1 pedicelled present; rachis internodes columnar, laterally sharply keeled, back rounded or obtusely keeled, lowest internode elongate, much exceeding sessile spikelet, successive internodes shorter. Sessile spikelet 6–7 mm; callus shortly pilose; lower glume lanceolate to ovate, leathery, back flat or slightly convex, obscurely ribbed, margins incurved, ciliolate, keeled and scabrid below apex; upper glume scabrid on keel toward apex; lower floret staminate, palea present; upper lemma and palea subequal, 2 styles arising separately from ovary apex, not elongate. Pedicelled spikelet variable, resembling sessile spikelet but slightly smaller or much reduced; pedicel stoutly oblong, straight. Fl. and fr. Aug–Oct.

* Ditches, moist meadows, river bank thickets, on damp sandy soils; 1100–2000 m. Sichuan, Yunnan.

This grass occurs at generally higher altitudes than Phacelurus latifolius. The pedicelled spikelet varies from well developed to much reduced, even in adjacent spikelet pairs on the same raceme.

Two specimens with solitary racemes have been described as new species in Rhytachne. That genus is not known in Asia and can usually be distinguished from Phacelurus by a much more delicate habit, cylindrical racemes, and a frequently foliaceous pedicel. The occasional occurrence of spikelet triads in this species is reminiscent of Mnesithea. However, it is excluded from that genus by its well-developed male lower floret, and also from Rottboellia by its free pedicel.