11 



a tuft of long, white, silky hairs by which they are blown about. The 

 roots of the milkweeds are somewhat brittle, whitish and thickened; 

 this is especially true of the showy milkweed (Fig. 4). The growth of 

 the root is mainly horizontal, as is shown in Fig. 5 The Root of the 

 Narrow-Leaved Milkweed. Sometimes, however, the roots penetrate 

 the soil like the roots of alfalfa. 



The milkweeds have a milky sap or juice which gives to them their 

 common name and distinguishes them from most other plants. How- 

 ever, a milky sap is found in many other plants, such as the Mexican 

 poppy, the dandelion and its close relatives, the wild lettuce, spurges, 

 and dog-banes. From all these plants having a milky juice, the milk- 

 weeds may be distinguished by the following differences : (1) the Mexi- 

 can poppy is spiny, while the milkweeds are not ; (2) the dandelion and 

 its near relatives have no erect stem, while the milkweeds have; (3) 

 the general appearance of the wild lettuce is quite different from the 

 milkweeds and its flower and flower clusters (heads) are like tiny dan- 

 delions and not at all like the flower or flower clusters of the milkweed ; 



(4) the spurges (Euphorbia) are mostly low, branching plants with 

 small leaves, the two halves of which are different in shape and size ; 



(5) some of the dog-banes might easily be mistaken for the narrow- 

 leaved milkweed, but they branch more freely and tend to be bushy, 

 at least toward the top. Their flowers are not scattered in dense clus- 

 ters and do not have hoods as in the milkweed. The pods are similar 

 to those of the milkweed but more slender; the seeds are also similar 

 but smaller and not so flattened. 



How to Distinguish the Narrow-Leaved Milkweed from the Showy Milkweed. 



The showy-leaved milkweed is quite abundant in Nevada, but it is 

 not nearly so poisonous as the milkweed with the long narrow leaves. 

 The two are easily distinguished by the following differences: (1) the 

 narrow-leaved milkweed has several leaves at each joint of the stem, 

 while the shown species has but two; (2) the leaves of the showy milk- 

 weed are much broader, from one-third to one-half as broad as they 

 are long; (3) the narrow-leaved milkweed has smooth pods, while the 

 showy species has pods roughened by projections. Figures 3 and 4 

 show the general appearance and characteristics of these two plants. 



Where the Milkweeds Grow. 



The milkweeds are widely distributed in Nevada. They require 

 fairly wet soil, and do not grow on the drier parts of the range. They 

 are common along irrigation ditches and streams, along roadsides, and 

 in pastures and washes and idle lands which have not been cultivated 

 for a number of years. In such locations the narrow-leaved kind is 

 more abundant. It has a wider distribution than the showy milkweed 

 or any of the other species found in this State. 



The milkweeds usually grow in full sunlight, although they may be 

 found in partly shaded places as in orchards and among willows and 

 cottonwoods along streams. 



In several places in Nevada the narrow-leaved milkweed has been 

 reported to be getting more abundant. Especially is this true along 

 the banks of irrigation ditches. Wherever irrigation systems have been 

 extended to new ground, this poisonous weed soon grows abundantly 

 along the ditch banks. 



