2.01 ARUNDINARIA Michx.
Lynn G. Clark
Plants arborescent or subarborescent, spreading or loosely clumped; rhizomes leptomorphic. Culms 0.5–8 m tall, to 3 cm thick, erect; nodes not swollen; supranodal ridges not prominent; internodes terete to slightly flattened or shallowly sulcate above the branches. Culm leaves: sheaths persistent or deciduous, mostly glabrous, abaxial surfaces sparsely pilose towards the margins and apices, margins ciliate; auricles usually present; blades erect or becoming reflexed, narrowly triangular to strap-shaped, abaxial surfaces sparsely pilose; leaves at tips of new shoots crowded into distinctive fan-shaped clusters or topknots, blades expanded as on the foliage leaves. Branch complements of 1 primary branch and 0–2 subequal secondary branches on young culms, rebranching to produce to 40+ secondary branches on older culms. Foliage leaves: sheaths persistent on the lower branch nodes; auricles usually present; fimbriae to 10 mm; blades finely cross veined abaxially, acuminate, blades of the ultimate branchlets often smaller, crowded into flabellate clusters of 3–7 leaves. Inflorescences open racemes or panicles; disarticulation below and between the florets. Spikelets 3–7 cm, with 6–12 florets, basal floret occasionally sterile, laterally compressed. Glumes 1–2, shorter than the lowest lemmas; lemmas to 2 cm, sometimes awned, awns about 4 mm; anthers 3; styles 3; paleas 2-keeled, not exceeding the lemmas. x = 12. Name from the Latin arundo, ‘reed’.
Arundinaria is a north-temperate genus with three native North American species. The most consistent differences among the North American species are seen in the vegetative characters, including the topknot leaf blades, foliage leaf blades, and features of the branch complements.
Arundinaria is sometimes taken as including several Asian species. Genera that used to be treated in Arundinaria include, for example, Fargesia Franch. and Sasa Makino & Shibata.Triplett and Clark (2010) showed that Arundinaria, Sasa, and Hibanobambusa tranquilans formed a subclade that was sister to two other subclades within the Arundinaria clade of the Arundinarieae.
SELECTED REFERENCES McClure, F.A. 1973. Genera of bamboos native to the New World (Gramineae: Bambusoideae). Smithsonian Contr. Bot. 9:1–148; Judziewicz, E.J., L.G. Clark, X. Londoño, and M.J. Stern. 1999. American Bamboos. Smithsonian Institution Press: Washington, D.C., U.S.A. 392 pp.; Triplett, J.K. and L.G. Clark. 2010. Phylogeny of the temperate bamboos (Poaceae: Bambusoideae: Bambuseae) with an emphasis on Arundinaria and allies. Systematic Botany 35:102-120; Triplett, J.K., K.A. Oltrogge and L.G. Clark. 2010.Phylogenetic relationships and natural hybridization amnng the North American woody bamboos (Poaceae: Bambusoideae: Arundinara). American Journal of Botany 471-492; Zhu, Z., C-D. Chu, and C. Stapleton. 2006. Arundinaria. Pp. 113–115 in Z.-Y. Wu, P.H. Raven, and D.-Y. Hong (eds.). Flora of China, vol. 22 (Poaceae). Science Press, Beijing, Peoples Republic of China and Missouri Botanical Garden Press, St. Louis, Missouri, U.S.A. 653 pp. http://flora.huh.harvard.edu/china/mss/volume22/index.htm.
For an interactive dichotomous key, click here; for an interactive, multientry key, click here.
1. Primary branches with 0–1 compressed basal internodes; culm internodes usually sulcate; culm leaves deciduous ... A. gigantea
1. Primary branches with 2–5 compressed basal internodes; culm internodes usually terete; culm leaves persistent to tardily deciduous ... 2
2. Foliage blades coriaceous, persistent, abaxial surfaces densely pubescent or glabrous, strongly cross veined; primary branches usually longer than 50 cm, basal nodes developing secondary branches; topknot blades 20–30 cm long ... A. tecta
2. Foliage blades chartaceous, deciduous, abaxial surfaces pilose or glabrous, weakly cross veined; primary branches usually shorter than 35 cm, basal nodes not developing secondary branches; topknot blades 9–22.5 cm long ... A. appalachiana
1. Arundinaria gigantea (Walter) Muhl.
River Cane, Giant Cane
Rhizomes normally remaining horizontal, sometimes hollow-centered, air canals absent. Culms 2–8 m tall, to 3 cm thick; internodes typically sulcate distal to the branches. Culm leaves deciduous; sheaths 9–15 cm; fimbriae 2.2–7 mm; blades 1.5–3.5 cm. Topknots of 6–8 leaves; blades 16–24 cm long, 2–3.2 cm wide, lanceolate to ovate-lanceolate. Primary branches to 25 cm, erect or nearly so, with 0–1 compressed basal internodes, lower elongated internodes flattened in cross section. Foliage leaves: abaxial ligules usually ciliate, sometimes glabrous; blades subcoriaceous, persistent, evergreen, 8–15 cm long, 0.8–1.3 cm wide, bases rounded, abaxial surfaces glabrous or pubescent, strongly cross veined, adaxial surfaces glabrous or almost so. Spikelets 4–7 cm, greenish or brownish, with 8–12 florets. Glumes unequal, glabrous or pubescent, lowest glumes obtuse to acuminate or absent; lemmas 1.2–2 cm, usually appressed-hirsute to canescent, sometimes pubescent only towards the base and margins. Caryopses oblong, beaked, without a style branch below the beaks. 2n = 48.
Arundinaria gigantea forms extensive colonies in low woods, moist ground, and along river banks. It was once widespread in the southeastern United States, but cultivation, burning, and overgrazing have destroyed many stands.
2. Arundinaria tecta (Walter) Muhl.
Rhizomes normally horizontal for only a short distance before turning up to form a culm, hollow-centered, air canals present. Culms usually shorter than 2.5 m tall, to 2 cm thick; internodes terete in the vegetative parts. Culm leaves persistent to tardily deciduous; sheaths 11–18 cm; fimbriae 1.5–8.5 mm; blades 2.5–4 cm. Topknots of 9–12 leaves; blades 20–30 cm long, 1.8–3.2 cm wide, lanceolate to ovate-lanceolate. Primary branches usually 50+ cm, basally erect and distally arcuate, terete, with 3–4 compressed basal internodes, basal nodes developing secondary branches, lower elongated internodes terete in cross section. Foliage leaves: abaxial ligules fimbriate to lacerate, sometimes ciliate; blades 7–23 cm long, 1–2 cm wide, coriaceous, persistent, evergreen, bases rounded, abaxial surfaces densely pubescent or glabrous, strongly cross veined, adaxial surfaces pubescent. Spikelets 3–5 cm, with 6–12 florets, the first occasionally sterile. Glumes unequal, glabrous or pubescent; lowest glume obtuse to acuminate or absent; lemmas 1.2–2 cm, glabrous or nearly so. Caryopses oblong, beaked, a rudimentary hooked style branch present below the beak. 2n = unknown.
Arundinaria tecta grows in swampy woods, moist pine barrens, live oak woods, and along the sandy margins of streams, preferring moister sites than A. gigantea. It grows only on the coastal plain of the southeastern United States.
3. Arundinaria appalachiana Triplett, Weakley & L.G. Clark
Rhizomes normally horizontal for only a short distance before turning up to form a culm, sometimes hollow-centered, air canals sometimes present. Culms 0.5–1 (1.8) m tall, 0.2–0.6 cm thick; internodes terete. Culm leaves persistent to tardily deciduous; sheaths 5.5–11 cm; fimbriae 1–4.6 mm; blades 0.8–1.4 cm. Topknots of 6–12 leaves; blades 9–22.5 cm long, 1.4–2.8 cm wide, linear, linear-lanceolate, or ovate-lanceolate. Primary branches usually shorter than 35 cm, erect, terete, with 2-5 compressed basal internodes, basal nodes not developing secondary branches. Foliage leaves: abaxial ligules glabrous or ciliate, fimbriate or lacerate; blades 5–20 cm long, 0.8–2 cm wide, chartaceous, deciduous, bases rounded, abaxial surfaces pilose or glabrous, weakly cross veined, adaxial surfaces pilose. Spikelets 3–5.5 cm, usually somewhat reddish purple, with 5–8 florets. 2n = unknown.
Arundinaria appalachiana grows on moist to dry slopes and in seeps. It is restricted to the southern Appalachians and upper piedmont.