A PERENNIAL DODDER. 4 1 



where the climatic conditions are favorable. Many herbace- 

 ous plants are of this sort. Some, however, when the tem- 

 peratures do not go too low, persist and continue to grow 

 year by year and become true perennials. The castor-oil 

 plant is a very good example and a well known one. In 

 favorable regions this plant attains the proportions of a tree. 

 At Torreon, Coahuila, trees twenty-five feet in height occur. 

 In the higher altitudes of Northern Zacatecas, where light 

 frosts occur, the castor-oil is often killed back to some extent. 

 Here, however, may be observed an analogous behavior 

 on the part of a species of dodder (Cuscuta) which grows on 

 various woody shrubs, among which are the guayule, Par- 

 then'nim argentatiim, the hojasen, a broad leaved composite, 

 and others. During the growing season the dodder affects 

 the new growths of the host plant in the usual fashion, wither- 

 ing away from the now woody growths of the previous year. 

 Developing luxuriantly, it spreads after the manner of its 

 kind, from branch to branch, often smothering its host,^nd 

 causing a partial or total failure to make growth in many 

 instances. It flowers and bears its fruit well into the autumn, 

 and often may be found with a few flowers even In January. 

 In any event, it seldom dies out, but, growing up among the 

 upper leaves of Its supporting twig. It becomes attached to 

 these also, and, forming an Irregular, more or less compact 

 clump, it passes a period of quiescence, during which growth 

 almost or quite ceases. In this condition the stems of the 

 dodder are reduced In size, especially those which extend 

 away from the support of the host. Its whole aspect be- 

 speaks its lessened activity. But It Is there ready for the 

 warmer weather of spring, and the advent of the rain which 

 will stimulate both it and its host. This fact accounts for the 

 rapid appearance of the parasite on the woody parts of the 

 plant, into the tissues of which It Is unable to penetrate. It 

 is In fact never found on the older growth excepting near the 

 new growth, where it has not yet succumbed to the secondary 

 thickening which destroys its hold on the host. — Francis E. 

 Lloyd. 



