THE PLANT AS A HOST 



907 



only occurs in the case of a proportion 

 of the roots. The plant has, too, inde- 

 pendent soil roots, and at the same time 

 develops perfectly green leaves. In mucli 

 the same way the Yellow Rattle {Rhinan- 

 thiis) of our pastures attaches some of its 

 roots to the underground runners of grass. 

 Yet so green is the fohage. and so abundant 

 the independent roots, that the plant can 

 only draw to a small extent upon the re- 

 sources of its host. These two species 

 are only tj'pes of several hundred plants, 

 existing in various parts of the world, 

 which hve partly at the expense of their 

 hosts by means of root attachment. 



There are few more curious plants than 

 the Toothwort (Lathraea), a species which 

 is wholly given over to parasitism. 

 Owing to the courtesy of Mr. E. J. 

 Allard, of Cambridge, the writer is able to 

 give an illustration of the Toothwort. 

 Though not common the plant has a wide 

 distribution, being found on 

 the roots of Poplar, Hazel, 

 and other trees. The Tooth- 

 wort is very easy to establish, 

 and it may be seen growing 

 in great abundance in several 

 botanic gardens. The ap- 

 pearance of the plant is very 

 singular, with its thick spikes 

 of pale lilac-tinted flowers. 

 Below the surface of the soil 

 it is possible to see the 

 manner in which the Tooth- 

 wort gets a living. From 

 the roots of the plant arise 

 suckers — in one species (L. 

 clandestina) as large as split 

 peas— by means of which the 

 roots of trees are penetrated. 

 Another plant of similar 

 habit to the Toothwort is 

 the Broomrape {Orohanche), 

 which grows as a parasite on 

 the roots of many common 

 plants, notably Broom and 

 other leguminous species. 

 The Broomrape has, of 

 course, no true leaves, and 

 looks more Hke a withered 

 flower-spike, so dingy is the 

 colouring of its inflorescence. 

 There are several species of 

 Orobanche to be found in 



Britain, one of which (0. major) is quite 

 frequently to be met with. It does not 

 seem that these root parasites are actually 

 very harmful' to the plants upon which 

 they force their attentions. 



One could not very well leave the 

 subject of plant parasites without a 

 reference to that wonder of the world, 

 the Rafflesia Arnoldi. This species, which 

 was discovered in Sumatra in 1818 by Dr. 

 Arnold, is so curiously modified that it is 

 almost reduced to one giant flower. The 

 blossoms are of colossal proportions, 

 measuring as much as three or four feet 

 in diameter. The Rafflesia usually 

 attaches itself to the roots of the trees 

 which are close to the trunk, and presents 

 a most striking appearance. The colour- 

 ing of the enormous petals is of a lurid 

 reddish brown shade, and the flower is 

 said to attract large numbers of winged 

 insects. 



TILLANDSIA, OR "OLD MAN'S BEARD.' 



