Elymus multiramosus Y. C. Zhang, 2024

Zhang, Yong-Chao, Wei, Xiao-Xing, Qin, Yan, Liu, Yong, Zhang, Shu-Zhen, Jia, Zhi-Feng & Liu, Wen-Hui, 2024, Elymus multiramosus (Poaceae), a new species from the north-western Qinghai-Tibetan Plateau, China, PhytoKeys 249, pp. 51-73 : 51-73

Elymus multiramosus Y. C. Zhang sp. nov.

Figs 1 , 2 , 3

Type.

China • Qinghai, Delhi City, Baishu Mountain . 37°29.23N, 97°23.45′E, 3722 m a. s. l., 10 October 2020, Yong-Chao Zhang (holotype at Qinghai-Tibetan Plateau Museum of Biology, HNWP 371720 ) .

Diagnosis.

Excluding the compound spike characteristic, Elymus multiramosus shares notable similarities with Elymus sibiricus in several traits. Both species have 1–2 spikelets per node, comparable glume lengths and vein numbers and similar lemma awn lengths. Their leaf morphology is also quite alike, with glabrous sheaths and comparable leaf blade dimensions. Additionally, their culm heights overlap, as both species exhibit tufted, erect culms, further highlighting their morphological resemblance. Similarly, Elymus multiramosus closely resembles Elymus nutans , especially in terms of spikelet number and glume features. Both species have 1–2 spikelets per node and nearly identical lemma awn lengths, though Elymus nutans tends to have slightly longer awns and an oblong-shaped glume ( Hua 2007). Their leaf blades are also alike, being smooth or nearly smooth, with similar dimensions, further emphasising the parallels between these two species. Lastly, Elymus dahuricus var. dahuricus and Elymus multiramosus display significant similarity in leaf morphology. Both species have glabrous sheaths and flattened leaf blades with matching lengths and widths. Their culm height ranges overlap considerably and both have tufted, erect culms. Despite these similarities, the subtle differences in their overall structure allow for their differentiation.

Elymus species are characterised by their perennial, tufted growth, typically lacking rhizomes and erect culms, sometimes decumbent at the base, with leaf sheaths split to the base. The leaves are linear or lanceolate, either flat or rolled, with membranous, non-ciliate ligules. The inflorescence is a spike, either erect or nodding, with 1–2 laterally compressed spikelets per node, each containing 2–10 florets that disarticulate below the fertile floret at maturity. The glumes are linear-lanceolate with 1–9 veins, often awned, and the lemmas are 5 - veined, rounded on the back and typically awned at the apex. The caryopsis fruit adheres to both the lemma and palea ( Hua 2007).

The new species is similar to Elymus sp. but it can be easily distinguished from that species by its compound spike, which has 3–4 spikelets with extended rhachillas at the base nodes. These rhachillas become much longer from the top to the base of the compound spike (Figs 4 – 6 ). The glumes of Elymus multiramosus are noticeably shorter than the first floret. The awns at the lemma apex range in length from 9 to 12 mm, surpassing the length of the lemma body. Elymus multiramosus is distinguished by stouter plants and longer inflorescences, which measure 17 to 19 cm, with spikelets primarily arranged on one side of the rachis. The glume apices are awn-tipped and the glumes themselves are lanceolate, exceeding the length of those in Elymus nutans by 4 to 7 mm.

Description.

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. Flower 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 length. Each primary branch has 3–7 nodes. Spikelet 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.

Phenology.

Elymus multiramosus flowers in early September and bears fruit in early October.

Etymology.

The specific epithet multiramosus is a compound of the Latin words multi meaning many and ramosus meaning branches to indicate a specific type of inflorescence.

Vernacular name.

Duō Zhī Pī Jiǎn Cǎo (Chinese pronunciation); 多支披碱草 (Chinese name).

Distribution and habitat.

The species is presently known only from a small area of Delingha City, west of Qinghai Province (37°29′14"N, 97°23′27"E). It grows on a dry rocky area of alpine, at an elevation of 3722 m a. s. l. Other plants in the vicinity of the plant 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.

Figures

Figure 1. Illumination of Elymus multiramosus Y. C. Zhang, sp. nov. A habit B compound spike C spikelet D primary branch E, F lemma G seed H base of plant with a fibrous root. Drawn by Yongchao Zhang.

Figure 2. One holotype specimen of Elymus multiramosus (371720), collected and preserved at Qinghai-Tibetan Plateau Museum of Biology (HNWP).

Figure 3. Elymus multiramosus in the wild, the top left is the locality found; the top right and bottom left are the compound spikes; the bottom right is the stem and leaf. Photographs by Yongchao Zhang.

Figure 4. The compound spike of Elymus multiramosus A – C are three compound spikes from Elymus multiramosus and D – F are compound spikes after seed threshing of the A – C separately, the mini-spike-like branches can be seen.

Figure 6. Details of compound spike of Elymus multiramosus during the flowering stage A spikelet B flower C, D stamens, pistil, anthers E anther F pollen, stigmas.