Galium aparine (catchweed bedstraw)

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Intermountain Flora
Annual, 1-10 dm tall, the stems weak but not especially slender, retrorsely hooked-scabrous on the angles, and tending to scramble on other vegetation, seldom much branched; leaves mostly in whorls of (6) 8, narrow, 1-nerved, cuspidate, mostly 1-4 cm long, retrorsely scabrous-ciliate on the margins and often also on the midrib beneath, uncinate-hispid above; inflorenscences small, mostly 3- to 5-flowered, borne on axillary peduncles that mostly surpass the subtending whorl of leaves and commonly bear a partial or complete whorl of reduced leaves at the summit, or the peduncles borne in sets of 3 at the ends of short, axillary branches; pedicels well developed, essentially straight, divaricate or ascending; corolla greenish-white, 4-parted, 1-2 mm wide; fruit (1.5) 2-4 (5) mm long, the segments approximate, covered with hooked bristles, or sometimes glabrous; 2 n reputedly = 20, 22, 42, 44, 48, 62, 64, 66, 68, 86, 88, approximating a polyploid series based on x = 11.

Cronquist, A., Holmgren, A.H., Holmgren, N.H., Reveal, J.L., and Holmgren, P.K. (1984) "Intermountain Flora" pg. 536, vol. 4, The New York Botanical Garden New York.