Caucasian Bluestem

This is a good fodder grass.

Bothriochloa bladhii hybridizes easily and frequently with some other species of Bothriochloa, and also with Capillipedium parviflorum and Dichanthium annulatum, blurring the boundaries between these genera and leading to a host of intermediates. New, apomictic races have arisen from among these products of introgression, causing much taxonomic difficulty. The name B. glabra has been applied to hybrids between B. bladhii and C. parviflorum.

Bothriochloa bladhii is most practicably treated in a broad sense to include all forms with an elongate inflorescence axis. Additionally, the habit is usually not stoloniferous, and the racemes are less obviously hairy than in B. ischaemum and B. pertusa.

Much of the taxonomic difficulty in this genus arises from the promiscuous habits of Bothriochloa bladhii whose rapacious introgression has vastly increased its own variability, blurred the boundaries with adjacent species to the point of extinction, and led to the emergence of new races from among the introgression products (DeWet & Harlan in Am. J. Bot. 53: 94-98. 1966; and Faruqi in Phyton (Austria) 13:285-303. 1969). The species is here treated in a wide sense to include all specimens with an elongated inflorescence. The only exception is the hybrid with Dichanthium annulatum which is sufficiently distinct from Bothriochloa to warrant a hybrid formula.

In some accounts (e.g. Bor, Grasses Burma Ceyl. Ind. Pak. and in Fl. Iran; Rozhev & Shishkin in Fl. URSS) Bothriochloa caucasica is recognised at species level. Its ancestry is complicated, but according to DeWet & Harlan (in Taxon 19:339. 1970) it probably arose from tetraploid races of Bothriochloa intermedia and Capillipedium parviflorum hybridising and then backcrossing to Capillipedium parviflorum, Although it does form a small, reasonably compact subpopulation of Bothriochloa bladhii, with the lower lemma of the sessile spikelet only about half as long as the lower glume, the distinction is not sufficient for it to warrant species rank. It is a better species from the cytogeneticist’s point of view than it is from the morphologist’s. It is not in fact a caucasian endemic, but occurs at least as far east as Chitral and doubtless could arise spontaneously wherever its parents grow together.

The various hybrids of Bothriochloa intermedia, according to DeWet & Harlan (1970), are as follows:

Bothriochloa intermedia x Bothriochloa ischaemum = Bothriochloa taiwanensis (included in Bothriochloa bladhii)

Bothriochloa intermedia x Dichanthium annulatum = " Dichanthium grahamii” (here kept apart from Bothriochloa)

Bothriochloa intermedia x Capillipedium parviflorum = Bothriochloa glabra (included in Bothriochloa bladhii)

(Bothriochloa intermedia x Capillipedium praviflorum ) x Capillipedium parviflorum = Bothriochloa caucasica (included in Bothriochloa hladhii)

Culm stout, about 45 cm long and 3 mm across. Blade about 7 mm wide; ligule about 1 mm long, ciliate on upper part and backside. Inflorescence a narrow panicle, about 10 cm long. Spikelets paired, dimorphic; the upper pedicellate, pedicel with a translucent longitudinal groove; the lower sessile and fertile, about 3.4 mm long, excluding the long awn. Lower glume subcoriaceous, lanceolate, acute, 3-nerved, about 3.2 mm long, margins inrolled; upper glume subcoriaceous, lanceolate, as long as the lower, 5-7-nerved, upper margins 2-keeled, hispid; upper lemma aristate, the awn 5 times the length of the lemma, flexuous, linear, 1-nerved, about 1.5 mm long; upper palea chartaceous, lanceolate, about 2.5 mm long, 2-nerved; anther about 1.2 mm long.

Perennial, tufted. Culms erect or decumbent at base, fairly robust, up to 130 cm tall, many-noded, nodes glabrous or appressed bearded. Leaf sheaths glabrous; leaf blades linear, 10–40 × 0.2–1 cm, hairy with tubercle-based hairs on both surfaces or abaxial surface glabrous, apex finely acuminate; ligule 0.5–1.5 mm. Inflorescence 9–20 cm, composed of many racemes borne in loose whorls along an elongate central axis, axis usually longer than lowest raceme, sometimes paniculate with branchedpeduncles; racemes 2–5 cm, often purplish, not obviously hairy; rachis internodes and pedicels thinly ciliate, shortly bearded at apex. Sessile spikelet 3–4 mm; lower glume narrowly oblong-lanceolate, herbaceous or cartilaginous and glossy, 5–7-veined, back slightly concave, glabrous or pubescent below middle, sometimes with a pit, margins keeled and scabrid near apex; awn of upper lemma 1–2.5 cm. Pedicelled spikelet barren or rarely staminate, narrower than sessile spikelet, sometimes pitted. Fl. and fr. Jul–Oct. 2n = 40, 60, 80.

Tufted perennial; culms 50-150 cm high, erect from a shortly rhizomatous base, often robust. Leaf-blades 10-55 cm long, 2-12 mm wide. Inflorescence with a central axis 4-20 cm long, the racemes numerous and borne loosely or densely in irregular whorls upon simple or branched peduncles; racemes 2-5 cm long (the lowest shorter than the central axis), pubescent. Sessile spikelet narrowly elliptic, 3-4 mm long; lower glume chartaceous, ± hairy below the middle, usually not glossy, with or without a pit; awn 10-25 mm long. Pedicelled spikelet glabrous, with 0-3 pits.

Distributed in tropical Asia and Pacific Islands to Australia and and tropical Africa.

Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Shaanxi, Sichuan, Taiwan, Xinjiang, Yunnan [Bhutan, India, Indonesia, Japan, Malaysia, Nepal, New Guinea, Pakistan, Thailand, Vietnam; Africa, SW Asia, Australia; introduced in America].

Distribution: Pakistan (Punjab, N. W. F. P, Gilgit & Kashmir); Old World tropics.

Exposed slopes, waste ground; 400–1600 m.

Bothriochloa intermedia (R. Br.) A. Camus in Ann. Soc. L. Lyon n. s. 76: 164. 1931; Hsu, Fl. Taiwan 5: 623. 1978; Koyama, Grass. Jap. Neighb. Reg. 441. 1987.
Andropogon intermedius R. Br., Prodr. Fl. Nov. Holl. 202. 1810;Honda 1. c. 341. 1930.
Andropogon intermedius var. punctatus sensu Honda, l. c. 342. 1930.
Bothriochloa haenkei (Presl) Ohwi, 1. c. 11: 168. 1942.
Bothriochloa glabra (Roxb.) A. Camus var. perfectior (Hook. & Arn.) Ohwi, I. c. ll: 167. 1942.
Bothriochloa intermedia var. punctata (Roxb.) Keng, Clav. Gram. Prim. Sin, 244. 1957.
Bothriochloa blahdii var. punctata (Roxb.) Steward, Kew Bull. 29(2): 444. 1974.

Perennials, Terrestrial, not aquatic, Rhizome short and compact, stems close, Stems nodes swollen or brittle, Stems erect or ascending, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stems branching above base or distally at nodes, Stem nodes bearded or hairy, Stem internodes solid or spongy, Stems with inflorescence less than 1 m tall, Stems with inflorescence 1-2 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades 2-10 mm wide, Leaf blades 1-2 cm wide, Leaf blades mostly flat, Leaf blade margins folded, involute, or conduplicate, Leaf blades mostly glabrous, Ligule present, Ligule an unfringed eciliate membrane, Inflorescence terminal, Inflorescence with 2 or more spikes, fascicles, glomerules, heads, or clusters per culm, Inflorescence a panicle with narrowly racemose or spicate branches, Inflorescence a panicle with digitately arranged spicate branches, Inflorescence branches more than 10 to numerous, Inflorescence branches paired or digitate at a single node, Inflorescence branches paired racemes, V-shaped, Peduncle or rachis scabrous or pubescent, often with long hairs, Rachis dilated, flat, central axis to which spikelets are attached, Rachis grooved, Flowers bisexual, Spikelets pedicellate, Spikelets dorsally compressed or terete, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets with 2 florets, Sp ikelets paired at rachis nodes, Spikelets in paired units, 1 sessile, 1 pedicellate, Pedicellate spikelet well developed, staminate, Spikelets bisexual, Spikelets disarticulating below the glumes, Spikelets disarticulating beneath or between the florets, Spikelets falling with parts of disarticulating rachis or pedicel, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes equal or subequal, Glumes equal to or longer than adjacent lemma, Glumes 3 nerved, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma 1 nerved, Lemma glabrous, Lemma apex acute or acuminate, Lemma distinctly awned, more than 2-3 mm, Lemma with 1 awn, Lemma awn 1-2 cm long, Lemma awned from tip, Lemma awn once geniculate, bent once, Lemma margins thin, lying flat, Lemma straight, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis.

Bothriochloa bladhii (commonly called, variously, Australian bluestem, Caucasian bluestem, forest-bluegrass, plains bluestem, and purple plume grass) is a Neotropic grass in the family Poaceae, found primarily in tropical Africa, and tropical and temperate Asia, and Australia. The type specimen was collected from China by Finnish botanist Peter Johan Bladh. The name of Bladh is honored in the specific epithet.