HARDWICKE' S SCIENCE-GOSSIP. 



i57 



PARASITICAL FLOWERING PLANTS. 

 By A. D. Webster. 



THIS curious and interesting class of plants has 

 but few British representatives, and these, 

 with perhaps one exception, by no means ornamental, 

 which will, to a great extent, account for the very 

 meagre information we at present possess regarding 

 the various species of which the family is composed. 



Fig. in. — Otobanche r.ipum. Broom-rape. 



Among British parasitical plants are the follow- 

 ing genera : the dodder (Cuscuta) ; broom-rape 

 (Orobanche) ; toothwort (Lathrsea) ; and mistletoe 

 ( Viscicm album) ; these again being subdivided into 

 about a dozen species, the following being a short 

 description of each, with original notes jotted clown 

 as opportunities offered. These parasites may be 

 divided into two kinds, viz. : those that attach them- 

 selves to the roots of different plants, as the broom- 



rape and toothwort, hence called root-parasites, and 

 those that live on the stem or branches as the mistle- 

 toe and dodder. 



The genus Orobanche comprises some half-a-dozen 

 species, most of which are difficult to recognise, and 

 have given a more than ordinary amount of trouble 

 in classification. They are fleshy herbs, with tuberous 

 roots, and never truly green, but generally of a 

 brown or russet colour. They are also destitute of 

 leaves, but covered instead with small, brown ob 

 reddish scales. 



These plants present the remarkable peculiarity 

 that each species is generally confined to or lives on 

 the same species of plants, thus the Orobanche major 

 feeds upon furze and broom ; O. rubra upon thyme ; 

 O. ramosa on hemp and lucerne ; O. minor on red 

 clover, turf, &c. ; O. elatior on various species of 

 composite, as centaury and milfoil ; and O. ccerulem 

 on Achillea millefolium. 



The greater broom-rape (O. major) is, as its 

 name denotes, our largest native species. Here I 

 have found this plant in considerable quantity, but, 

 strange to say, always parasitic on furze and never on 

 broom as the popular name would lead one to 

 suppose. In most botanical works it is also stated 

 to be found in greatest quantity on broom, less so on 

 furze. 



This cannot be attributed to the want or absence 

 of broom here, for in several cases where I have 

 found the broom-rape growing in abundance, there 

 were also in close proximity numberless plants of the 

 broom, so that had a preference been given, as is. 

 generally believed, there is no doubt it would have 

 been found on the latter plant, especially under such, 

 favourable circumstances. I have also frequently 

 noticed that this broom-rape seems to prefer living 

 on such plants as grow in a warm, dry, usually 

 sandy soil and sheltered situation, as on the more 

 exposed parts of the ground, although furze may be 

 growing in quantity, the broom-rape gradually 

 disappears, whereas on the southern and consequently 

 warmer side it is found in abundance. The root is 

 tuberous and composed of a number of lanceolate, 

 fleshy scales, somewhat similar in appearance to. 

 those of the lily, and so closely packed together at 

 the centre that when cut across with a sharp knife 

 the root appears quite solid. The scales on the outer 

 portion of the root are, however, less firmly packed, • 

 and the points slightly protruding. When bursting 

 through the ground the shoot in size, shape, and 

 appearance very closely resembles that of our garden 

 asparagus, even the peculiar purplish hue, so char- 

 acteristic of that plant when in a young state, is not 

 wanting in the orobanche. The reproduction of 

 this plant, which is both marvellous and interesting, 

 is affected either by seed or increase of the root. In 

 the latter case the new root or tuber, as in our 

 common Orchis, is produced alongside that of the 

 one supporting the present plant, and inwards 



