IN THE CORN FIELD 295 



only m sunny weather. The fruit is a httle globular capsule, 

 enclosed in the persistent calyx, splitting transversely into two 

 hemispheres when ripe. 



The Climbing Bistort {Polygonum convolvulus — order Poly- 

 gonacece), also known as the Chmbing Buckwheat, Climbing Per- 

 sicaria, and Black Bindweed, is a very troublesome corn-field weed, 

 with the climbing habit of the Convolvulus, often strangling the 

 plants round which it t^^dnes its angular stem. It varies from one 

 to four feet in height ; and its alternate leaves are heart-shaped or 

 arrow-shaped, pointed, with short membranous stipules at the base 

 of the stalk. The flowers are small, pale green, in Httle loose clusters 

 of from four to twelve. The lower clusters are stalked in the axils of 

 the leaves, and the upper ones form irregular, terminal racemes. 

 The five segments of the calyx are bluntly keeled, and occasionally 

 winged ; and the three outer ones closely envelop the fruit — a 

 triangular nut. The plant flowers from July to September. 



At least two or three of the Spurges [Ewphorhiacece) are com- 

 monly seen in cultivated fields, but one in particular — the Dwarf 

 Spurge {Euphorbia exigua) — is common in corn fields. It is a 

 slender, smooth plant, usually from two to ten inches high, with 

 several ascending stems diverging from near the base. The little 

 yellow flowers are in terminal umbels of from three to five rays, some- 

 times very much contracted ; and their glands (see p. 207) are 

 crescent-shaped, with their fine points turned outwards. The time 

 of flowering is July to October. 



Our last example of the corn-field plants is the Wild Oat Grass or 

 Havers [Avena fatua) — an erect grass, two or three feet high, with 

 rough leaves, and stem hairy at the joints. Its flowers form a loose, 

 spreading panicle, from six to nine inches long ; with three-flowered 

 spikelets, about an inch long, on very slender stalks, erect at first 

 but afterwards drooping. The outer glumes are about three 

 quarters of an inch long, tapering to a bristly point, often tinged 

 with purple ; and the inner ones, two or three in number, are 

 a Httle shorter, cleft at the top into pointed lobes, and covered 

 outside with yellowish-brown haus. The awn is about twice as 

 long as the spikelet, twisted at the base, and usually bent near the 

 middle. This grass flowers during June and July. 



