26 BULLETIN" 119, U. S. DEPARTMENT OF AGRICULTURE. 



THE URD, OR BLACK GRAM. 



The urd, or black gram {PJiaseolus mungo L. ; PI. VI), is very similar 

 to the mung and the botany of the two has become much confused. It 

 is easily distinguishable from the mung, however, by the much shorter, 

 stouter, very hairy pods and larger oblong seeds, which vary in 

 color from blackish to olive. The flowers are fully self-fertile. It is 

 cultivated only in India. According to Mollison (1901, p. 88) an area 

 equal to about 250,000 acres is devoted to this crop in the Bombay 

 Presidency, and Duthie and Fuller (1882, p. 39) say that the area in 

 the Northwestern Provinces and Oudh is about 260,000 acres. 



In botanical characters the urd is very similar to the mung, but 

 in habit the plants are lower and spreading, the branches usually 

 procumbent. The very hairy stems are never twining in any variety 

 grown at Arlington farm, but a twining variety occurs in India and 

 is distinguished as a crop under the name "tikari." 



There is still room for slight doubt regarding the botanical name 

 to be applied to the urd. There is no specimen labeled PJiaseolus 

 mungo in the Linnsean herbarium. Prain (1897, p. 423) points out, 

 however, that Linnseus's description of PJiaseolus mungo accords 

 better with the tikari than with any related species, and his judg- 

 ment, based on a wide knowledge of the Indian species, can hardly 

 be controverted. 



From the standpoint of a forage or cover crop the urd is inferior 

 to the mung, as it makes much less herbage. The pods, however, 

 do not shatter so readily, so little of the seed is thus lost. Owing to 

 the low, spreading habit, however, it is necessary to pull the plants 

 in harvesting. The best yield of seed at Arlington farm was 13.6 

 bushels per acre from No. 17308. The average yield in India was 

 stated to be about 7 bushels per acre in 1912. 



The urd is utilized as a green-manure crop in Trinidad under the 

 name of " woolly pyrol," and wherever Hindoo laborers are numerous 

 in the West Indies they cultivate this plant for food. 



In warm, moist weather the urd is much subject to mildew (Ery- 

 siphe polygoni). It is also affected by both the leaf -spots that 

 attack the mung and the cowpea. 



The habit of the urd is such that it can not be as easily harvested 

 for hay or seed as the mung. It is difficult to see wherein it can 

 compete as a forage crop under American conditions with either the 

 cowpea or the soy bean. As human food the seeds seem far less 

 desirable than other species. 



INTRODUCTION. 



One variety of the urd, erroneously named Dolichos cultratus, was 

 grown in Louisiana in 1898 (Dodson and Stubbs, 1898, p. 37). It 

 was early enough to mature and shatter its seeds by September 1, 

 so that when it was plowed under a good second crop was produced. 



