Poa ussuriensis Roshev.

Poa ussuriensis is common on the Russian side of the Chinese border east and west of Vladivostok. Poa radula Franchet & Savatier was reported in FRPS (9(2): 113–114. 2002) from Jilin, but it is doubtfully present in China. According to Probatova (in Tzvelev, Sosud. Rast. Sovetsk. Dal'nego Vostoka 1: 283. 1985), P. radula is a species of Sakhalin, the Kuril Islands, and S Kamchatka, but is not found elsewhere in the Russian Far East, China, or Japan. Chung (Korean Grass. 72. 1965) reported it from S Korea, but not N Korea or China; Japanese authors have not mentioned it for Korea or China; and Kitagawa (Neo-Lineam. Fl. Manshur. 102–105. 1979) did not list it for Manchuria. Poa radula can be difficult to distinguish from P. ussuriensis: it has a broader leaf blade, (3–)4.5–10 mm wide, longer ligule, (1.5–)2.5–4 mm, larger spikelets (5–)6–8(–10) mm, and hexaploid chromosome number.

Weakly perennial, loosely tufted. Culms erect, 30–80 cm tall, ca. 0.8 mm in diam., scabrid below nodes, nodes 3 or 4(–5), 2 or 3 exposed. Leaf sheaths very compressed with a winged keel, 4–13 cm, 1/2–1 × as long as blade, uppermost closed for 2/3–3/4 of length; blade flat or weakly folded, thin, deeply keeled, 2–15 cm × (1.5–)2–3(–4.5) mm, adaxially scabrid, margins densely scabrid; ligule (0.5–)1–2(–2.5) mm, abaxially scabrid, apex truncate to obtuse, collars scabrid, margins glabrous. Panicle open, lax, diffuse, 7–20 cm, broad, longest internodes 3–5 cm; branches eventually spreading, lax, 2–5 per node, slender, scabrid on and between angles throughout, longest to 12 cm with 3–13 loosely arranged spikelets in distal 1/3. Spikelets oblong-lanceolate, light green, (3–)4–6 mm, florets 3–5(–6); vivipary absent; rachilla internodes ca. 1 mm, smooth, glabrous; glumes unequal, acute, keels sparsely scabrid, lower glume 1.5–2 mm, 1-veined, upper glume 2.5–3 mm, 3-veined; lemmas 3–4 mm, apex acuminate, keel villous for 2/3 of length, marginal veins for 1/3, intermediate veins prominent, area between veins minutely bumpy, glabrous; callus sparsely webbed; palea smooth or minutely bumpy between keels, keels scabrid. Anthers 0.4–1 mm. Fl. and fr. Jun. 2n = 28, 42.

Deciduous forests, mixed forests, glades, riparian gravels. Heilongjiang, ?Jilin (expected) [Korea, Russia (Far East)].

Poa ussuriensis f. angustifolia I. C. Chung; P. ussuriensis f. scabra I. C. Chung.