Multi-branch wild rye (Elymus multiramosus) from China has similarities with Elymus nutans Griseb

NEWS - Multi-branch wild rye (Elymus multiramosus Y.C. Zhang, sp. nov.) reported from Delingha City, west of Qinghai Province, China, which has similarities with Elymus nutans Griseb. However, it can be easily distinguished from other species by its compound spikes characterized by elongated rhachilla at the base of the main axis, producing 3–6 mini-thorn-like branches.

Elymus L. is the most extensive genus in Triticeae, characterized by polyploid and mostly short-lived perennial grasses including about 172 species from the Arctic to subtropical regions, adapting to diverse environments such as grasslands, semi-deserts and mountains.

Elymus provides important annual forage in temperate regions and especially in the Qinghai-Tibet Plateau. In October 2020, in Delingha City, west of the Qinghai-Tibet Plateau, plants with compound spikes were found in a dry and rocky alpine grassland area.

Elymus multiramosus is a herb with culms are usually erect, sometimes slightly decumbent at base, 82–95 cm tall. Leaf-sheath glabrous; leaf blade flat, 18–22 × 0.5–0.7 cm, glabrous or adaxial surface slightly pubescent.

Compound spike pendulous, slightly lax, 17–19 cm; rachis margin scabrous, no ciliolate, rachis knot dilated. Compound spike includes a clear main shoot axis and a series of lateral branches produced by the main shoot.

Flowers are formed from the top of the main axis and primary branches from the base to the middle of the main axis. A total of 3–6 primary branches are formed in the main axis, 2–4 cm long. Each primary branch has 3–7 nodes.

Spikelets usually 2 per node, with 2 or 3 florets. Glumes lanceolate, 4–7 mm, 3-veined, glabrous, scabrous along veins, apex with awn 1.5–2.2 mm. Lemma lanceolate, 3-veined, obscurely at the base, scabrous or puberulent at the apex and edge; first lemma 7–10 mm; awn 9–12 mm. Palea equalling lemma, ciliolate along keels, puberulent between keels.

The new species is similar to Elymus sp. but can be easily distinguished by the compound spike, which has 3–4 spikelets with an elongated rhachilla at the base node. The rhachilla becomes much longer from the top to the base of the compound spike.

The glumes of E. multiramosus are noticeably shorter than the first floret. The awns at the apex of the lemma range from 9–12 mm, extending beyond the length of the body of the lemma. E. multiramosus is distinguished by its more robust plant and longer inflorescence (17–19 cm), with spikelets mainly arranged on one side of the rachis. The glume apices are awn-tipped and the glumes themselves are lanceolate, exceeding the glume length in E. nutans by 4–7 mm.

E. multiramosus is similar to Elymus sibiricus in having 1–2 spikelets per node, comparable glume length and number of veins, and similar awn lemma length. Leaf morphology is also similar, with glabrous sheaths and comparable leaf blade dimensions. Stem heights overlap, as both species exhibit tufted and erect stems.

E. multiramosus is very similar to E. nutans, especially in spikelet number and glume features. Both species have 1–2 spikelets per node and nearly identical awn lemma lengths, although E. nutans tends to have slightly longer awns and oblong glumes. The leaf blades are also similar, smooth or nearly smooth, with similar dimensions.

Elymus dahuricus var. dahuricus and E. multiramosus show significant similarities in leaf morphology. Both species have glabrous sheaths and flat leaf blades of similar length and width. The stem height ranges overlap significantly and both have erect, tufted stems.

E. multiramosus flowers in early September and fruits in early October. The specific epithet multiramosus is a combination of the Latin words multi meaning many and ramosus meaning branch to indicate a particular type of inflorescence. The local names are Duō Zhī Pī Jiǎn Cǎo (Chinese pronunciation) and 多支披碱草 (Chinese name).

The new species is known only from Delingha City, western Qinghai Province. It grows in dry, rocky Alpine areas at an elevation of 3,722 m. Other plants nearby include Juniperus przewalskii Kom., Agropyron cristatum J.Gaert., Elymus dahuricus Turcz. var. cylindricus Franchet, Neotrinia splendens (Trin.) M. Nobis, P.D. Gudkova & A. Nowak etc.

Original research

Zhang Y-C, Wei X-X, Qin Y, Liu Y, Zhang S-Z, Jia Z-F, Liu W-H (2024). Elymus multiramosus (Poaceae), a new species from the north-western Qinghai-Tibetan Plateau, China. PhytoKeys 249: 51-73. https://doi.org/10.3897/phytokeys.249.127632, DOI:10.3897/phytokeys.249.127632

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