88 THE r*JDIAA T A WEED BOOK. 



The rough or tall einquefoil (P- monspeliensis L,), stem 1-3 

 feet high, erect, rough-pubescent, leaflets 3, flowers small, yellow, 

 numerous in terminal cymes, is frequent in moist soils throughout 

 the State, being especially troublesome in clover fields. It flowers 

 from June to August. Remedies: close cutting in spring or early 

 summer; cultivation. 



The Pea Family.— PAPILIONACE^. 



Herbs, shrubs, vines or trees with alternate, mostly compound, 

 stipulate leaves. Flowers butterfly-shaped, like those of the sweet 

 pea, mainly in spikes, heads or racemes; calyx 4-5 -toothed or cleft; 

 petals usually consisting of a broad upper one (the standard or 

 banner), two side ones (the wings), and two lower or front ones, 

 more or less united (the keel) ; stamens 5-10, all united at the base 

 into one group (monodelphous) ; two groups (diadelphous}, or 

 separate; ovary usually 1-eelled, containing 1 to many ovules. 

 Fruit a pod, 1 to many seeded, usually splitting into 2 valves. 

 (Figs. 9, c, d; 11, c; 14, k, I.) 



A large family, of which the peas, beans and clovers are fa- 

 miliar and important cultivated members. All have the fruit in 

 the form of legumes or pods which vary much in size and shape. 

 Rarely, as in alfalfa, they are coiled like snail shells; again they 

 are like the achenes of buttercups but differ in opening down both 

 sides to release the seeds. In one group, the trefoils and bush 

 clovers, they are broken up into joints, each joint containing a 

 single seed; in most species, however, they are like those of the 

 pea or bean. To the farmer the members of the pea family are 

 especially important, since they harbor on the roots bacteria which 

 produce small nodules (Fig. 7.) enabling the plants to gather 

 and store nitrogen from the air. It is this stored nitrogen which 

 renders clover, cow-peas, etc., such valuable fertilizers. About 90 

 members of the family are known from the State, a half dozen or 

 so of which may be classed as weeds. 



40. Cassia MARYi^NnrcA L. Wild Senna. (T. N. 3.) 



Erect or spreading, often branched, 3-8 feet high; leaves pinnate; 

 leaflets 12-20, oblong, obtuse, 1-2 inches long; flowers not butterfly- 

 shaped but nearly regular, yellow, showy, in upper axillary racemes; 

 jietals 5, nearly equal; stamens 10, separate, the upper 3 imperfect. Pod 

 linear, curved, 3-4 inches long. J inch wide. Seeds hard, gray, 3/1G of an 

 inch long, half as wide. (Fig. 54.) 



Abundant on moist hillsides, in lowland meadows and pastures 

 and along sand and gravel bars in the southern half of the State; 



