LEGUMINOSAE (PULSE FAMILY) 



223 



hay than in those that are green in the field. Its action is slow, 

 often several weeks intervening before death. If recovery comes it 

 is not complete, the animal being never so well again as before the 

 attack of Crotalism. The weed is a relative of the dreaded Loco- 

 weed of the plains, but does not cause the animals to "go plumb 

 crazy, " as does that plant. (Fig. 159.) 



The plant is small, seldom more than a foot in height, with a 

 much-branched and hairy stem growing 

 from a small, straight root. Leaves 

 alternate, nearly sessile, lance-shaped, 

 one or two inches long, pointed at both 

 ends, entire or slightly wavy, with edges 

 softly hairy ; they have curious stipules, 

 shaped like an arrow-head, point down, 

 with the ears sticking up on each side of 

 the leaf and the point decurrent on the 

 stem for a part of its length. Flowers 

 yellow and very small, shaped like pea- 

 blossoms, that is, with a corolla of five 

 irregular petals, the upper one larger 

 than the others, and enclosing them in 

 the bud ; this broad upright petal is 

 called the standard and is usually turned 

 backward ; two lateral petals or wings, 

 obliquely spread and outside of the 

 two lower ones which cohere at their 

 edges, forming the keel, which usually 

 encloses the stamens and pistil. In this 

 species the stamens are ten, one separate and nine of them united 

 into a tube, cleft on its upper side, the anthers of two lengths and 

 sizes, alternating with each other; calyx two-lipped, the two 

 upper lobes broadest, all five long-pointed and softly hairy. The 

 flowers grow in clusters of two or three on slender, axillary pe- 

 duncles. Pods black, very hard and brittle, about an inch long 

 but swollen much larger than the small, black seeds within, which 

 break from their hold when ripe and rattle about inside the stiff, 

 thin walls. In winter these light pods are blown long distances 

 over the snow, and they can float like a boat on water. 



j. 159. Rattlebox (Cro- 

 talaria sagittalis) . X 3. 



