26.03   MISCANTHUS Andersson

Revised 5 March 2008 See comment

Plants perennial; cespitose, sometimes rhizomatous. Culms 40-400 cm, erect. Leaves not aromatic; sheaths open; ligules membranous, truncate, ciliate; blades flat. Inflorescences terminal, ovoid or corymbose panicles, with elongate rachises and numerous ascending, spikelike branches; branches usually more than 10 cm long, with unequally pedicellate spikelet pairs, spikelets homogamous and homomorphic; disarticulation below the glumes. Calluses short, blunt, pilose, with fine hairs, hairs often exceeding the spikelets. Glumes membranous to coriaceous; lower glumes broadly convex to weakly 2-keeled, without raised veins; lower florets sterile; upper florets bisexual; upper lemmas entire and unawned or bidentate and awned from the sinuses; anthers 2 or 3. Pedicels free. x = 19. Name from the Greek mischos, pedicel, and anthos, flower, both spikelets ( flowers ) being pedicellate.

Miscanthus is a genus of approximately 25 species. Most of the species are native to southeast Asia; a few extend into Africa. Some species hybridize with Saccharum, from which Miscanthus differs in its non-disarticulating branches and unequally pedicellate, rather than sessile-pedicellate, spikelets.

The five species found in the Flora region are all grown as ornamentals because of their large, plumose panicles and striking growth habit. They flower in late summer to fall. The differing chromosome numbers within Miscanthus sinensis and M. sacchariflorus are associated with morphological differences in Japan, but it is not known if this is true for cultivated plants.

Miscanthus × giganteus J.M.Greef & Deuter ex Hodk. & Renvoize is being grown in the U.S. It is being considered as a bioenergy source. The key will be amended and a description and illustration added later. Currently it is included in Saccharum.

1.   Miscanthus floridulus (Labill.) Warb. ex K. Schum. & Lauterb.
Giant Chinese Silvergrass

Plants cespitose, forming large clumps. Culms 1.5-4 m tall, 8-16 mm thick below. Leaves crowded at the base; sheaths glabrous or sparsely pubescent, margins glabrous or ciliate; ligules 1-3 mm; blades 30-80 cm long, 15-40 mm wide, adaxial surfaces pubescent near the bases, glabrous elsewhere, midveins whitish, conspicuous both ab- and adaxially. Panicles 30-50 cm long, 10-20 cm wide, exserted, dense, ovoid-ellipsoid, white, usually with more than 15 branches; rachises 25-40 cm, hispid-pubescent, 3/4-4/5 as long as the panicles; branches 10-25 cm long, 8-10 mm wide, often branched at the base; internodes 3-5 mm, glabrous. Shorter pedicels 1-1.5 mm; longer pedicels 2.5-3.5 mm, becoming somewhat recurved. Spikelets 3-3.5 mm, lanceolate to lance-ovate; callus hairs 4-6 mm, to twice as long as the spikelets, white. Lower glumes glabrous or puberulent distally; awns of upper lemmas 5-15 mm, weakly geniculate. 2n = 36, 38, 57.

Miscanthus floridulus is the most widespread species of Miscanthus in southeast Asia. The culms are used for arrow-shafts in Papua New Guinea and as support and drying racks for climbing vegetables and tobacco in the Philippines. In North America it is grown as an ornamental. The blades of the lower leaves tend to fall off in late summer, leaving the culms naked at the base. It is tolerant of wind and salt spray.

2.   Miscanthus sinensis Andersson
Eulalia

Plants cespitose, forming large clumps, with short, thick rhizomes. Culms 60-200 cm tall, 3-7 mm thick below. Leaves predominantly basal; sheaths mostly glabrous, throats pilose; ligules 1-2 mm; blades 20-70 cm long, 6-20 mm wide, midveins conspicuous abaxially, 1-2 mm wide, whitish. Panicles 15-25 cm long, 8-28 cm wide, dense to loose, usually with more than 15 branches; rachises 6-15 cm, 1/3- 2/3 as long as the inflorescences; branches 8-15(30) cm long, about 10 mm wide, sometimes branched at the base; internodes 4-8 mm, glabrous. Shorter pedicels 1.5-2.5 mm; longer pedicels 3.5-6 mm, slightly recurved at maturity. Spikelets 3.5-7 mm, lanceolate to lance-ovate; callus hairs 6-12 mm, to twice as long as the spikelets, white, stramineous to reddish. Glumes subequal; lower glumes 3-veined, ciliolate on the margins; upper glumes 1-veined; awns of upper lemmas 6-12 mm, geniculate below. 2n = 38, 40, and dysploids from 35-42.

Miscanthus sinensis is native to southeastern Asia. It is frequently cultivated in the United States and southern Canada, and is now established in some parts of the United States. Approximately 40 forms and cultivars are available, some having white-striped leaves, others differently colored callus hairs and, consequently, differently colored panicles.

3.   Miscanthus nepalensis (Trin.) Hack.
Himalaya Fairygrass

Plants cespitose, shortly rhizomatous. Culms 40-80(150) cm. Sheaths more or less keeled, with scattered hairs, particularly below the collar; ligules 2-3.5 mm, obtuse, lacerate and shortly pubescent; blades 20-60 cm long, 4-10 mm wide, stiff, flat or folded, abaxial surfaces with scattered fine hairs, adaxial surfaces glabrous. Panicles 10-20 cm, flabellate, golden brown, with more than 15 branches; rachises about 1/2 as long as the panicles; branches 3.5-10.5 cm, ascending. Shorter pedicels 1.5-2 mm; longer pedicels 2.5-3.5 mm. Spikelets 2-2.8 mm; callus hairs 3-4 times longer than the spikelets, golden brown. Lower glumes hairy on the lower margins, hairs to 3 times longer than the glumes; awns of upper lemmas 9-13 mm, exceeding the glumes, flexuous to weakly geniculate. 2n = 40.

Miscanthus nepalensis is native from Pakistan through the Himalayas to Myanmar. It is cultivated occasionally in the Flora region. Edgar and Conner (2000) report that, in New Zealand, M. nepalensis has escaped cultivation and is spreading.

4.   Miscanthus sacchariflorus (Maxim.) Hack.
Amur Silvergrass, Miscanthus

Plants rhizomatous, rhizomes 3-6 mm wide. Culms 60-250 cm tall, 5-8 mm thick below; nodes pilose. Leaves evenly distributed; ligules 0.5-1 mm; blades 20-80 cm long, 0.5-3 cm wide, adaxial surfaces densely pilose basally, midribs prominent, whitish. Panicles 15-40 cm long, 8-16 cm wide, white to yellowish-brown, usually with more than 15 branches; rachises 4-10 cm; nodes pilose; branches 10-35 cm long, about 10 mm wide, sometimes branching at the base. Shorter pedicels 1.5-3 mm; longer pedicels 3-7 mm, strongly curved at maturity. Spikelets 4-6 mm; callus hairs 2-4 times as long as the spikelets, copious, white. Lower glumes 2-keeled above, margins densely pilose distally, hairs to 15 mm; upper glumes 4-5 mm, 3-veined, margins ciliate distally; awns of upper lemmas absent or short, not exceeding the glumes. 2n = 38, 57, 64, 76, 95.

Miscanthus sacchariflorus is native to the margins of rivers or marshes in temperate to north-temperate regions of eastern Asia, and appears to require cold and humidity for optimum growth. It has escaped from cultivation in various parts of the Flora region. It combines a large, plumose panicle with recurving leaves that turn orange in the fall.

5.   Miscanthus oligostachyus Stapf
Small Japanese Silvergrass

Plants cespitose, rhizomatous. Culms 80-150 cm tall, 2-3 mm thick below, few together or solitary; nodes finely pubescent. Sheaths mostly glabrous, pilose near the summits; ligules 2-3 mm, rounded; blades well-developed only on the cauline sheaths, 8-35 cm long, 6-25 mm wide, adaxial surfaces densely pilose basally. Panicles long-exserted, loose, with 2-5 erect to suberect branches; branches 7-15 cm, densely pilose, with white or purplish-white hairs. Shorter pedicels 1.5-2 mm; longer pedicels 5-6 mm, sulcate on 1 side. Spikelets 6-8 mm; callus hairs from 1/2 as long as to equaling the spikelets, silky, white. Lower glumes 6-8 mm, sparsely pilose, 2-keeled above, 2-toothed, teeth densely white-ciliate; upper glumes equaling the lower glumes, 3-5-veined; awns of upper lemmas (4)8-15 mm, twisted at the bases; anthers 2.5-3 mm. 2n = 38.

Miscanthus oligostachyus is a native of Japanese and Korean forests that is sold as an ornamental species in the United States. It does best in regions with cool summers. Koyama (1987) recognized three subspecies of M. oligostachyus; they have not been evaluated for this treatment.

COMMENT added 5 March 2008 Miscanthus ×giganteus, Giant Miscanthus