Weeds
Poa annua L. - Annual Meadow-Grass, Annual Blue Grass.
Systematic position.
Family Poaceae (Graminea), genus Poa L.Biological group.
Annual or biannual, rarely perennial, weed.Morphology and biology.
The plant forms small, friable tussocks with coronal roots. Stalk 5-35 cm in height, frequently decumbent. Leaf plate 0.5-4 mm in width. Sheaths bare and smooth. Ligule 1-3 mm in length. Inflorescence paniculate, sprawling during flowering, pyramidal. Panicle reaches 7 cm in length, with relatively few spikelets and smooth twigs located in nodes in groups of 1 or 2. Spikelets 3-6 mm in length, with 3-7 flowers and blunt spicate scales. Lower spicate scale has one vein; upper one has 3 veins. The lower floral scale has 5 veins, usually long-pubescent along keel and edge veins. Blossoming occurs in May-September; fructification occurs in June-October.Distribution.
It.s an almost cosmopolitan weed distributed all over the globe. A common plant in all territories of the former USSR, excluding the far north and the deserts of Central Asia.Ecology.
The species is not limited to certain soil types, living both in rather poor and rather rich soils. Occurs in excessively alluvial soils. Grows along sandy and pebbly stream sides and in ruderal habitats; abundant in intensive pastures and in damp meadows.Economic significance.
Ruderal-segetal weed. A common weed plant among vegetable crops. Can rapidly spread in fields with fertile soils. Control measures include agronomical actions and chemical weeding.Related references.
Gubanov I.A., K.V. Kiseleva, V.S.Novikov, V.N.Tikhomirov. 2002. The illustrated key to plants of Middle Russia. V.1, Moscow: Tovarishchestvo nauchnykh izdanii KMK, Institut tekhnologicheskikh issledovanii, p. 286 (in Russian).Maevskii P.F. 1954. Flora of middle belt of the European part of the USSR. Moscow & Leningrad: Selkhozgiz, 912 pp. (in Russian).
Ramenskii L.G., Tsatsenkin I.A., Chizhikov O.N., Antipin N.A. 1956. Ecological evaluation of the fodder lands by vegetation cover. Moscow, 472 pp. (in Russian).
Shishkin B.K. (Ed.). 1963. The botanical atlas. Moscow & Leningrad: Izdatel.stvo sel.skokhozyaistvennoi literatury i plakatov, p. 311 (in Russian).
Ul'yanova T.N. 1998. Weed plants in the flora of Russia and other FSU countries. St. Petersburg, 233 pp. (in Russian).