BRITISH PARASITIC FLOWERING PLANTS, WITH A LIST OF 



THE SPECIES. 



By Jajies Satjndees. 



Eead at St. Albans, 8th December, 1897. 



(Abridged.) 



The Parasitic Flowering Plants of Britain, with their allies the 

 Saprophytes, number 33 species and 6 sub-species or varieties, of 

 which 23 species and 1 sub-species are known to occur in the 

 South Midlands. 



The true Parasites obtain either a part or the whole of their 

 nourishment from the host plant to which they are attached. Of 

 the British forms the mistletoe is the only species which is truly 

 parasitic throughout its career, and it is distinguished also as being 

 the only British shrub which belongs to this group. All the other 

 parasites germinate in the soil, and, as the reserve material 

 provided for their embryos is but small, the seedling must 

 speedily attach itself to another plant, or it will perish. Hence 

 the vast number of seeds which most of the species produce. Of 

 these seeds only a small proportion germinate, and of those which 

 do so a still smaller number succeed in attaching themselves to the 

 plants necessary for their continued existence. 



The subaerial and subterranean organs of chlorophyll-producing 

 plants are subject to the attacks of these parasites. The broomrapes 

 and the toothwort fasten themselves to the roots of their host, and 

 the dodders adhere by suckers to the stems and foliage of such 

 plants as are adapted for their sustenance. 



Some parasites bear green leaves which are often small and not 

 of a healthy hue. By these they obtain part of their food by 

 assimilation from the atmosphere, and this is supplemented by that 

 which can be derived from the plants to which they are attached. 

 Examples of these are furnished by Bartsia, yellow rattle, and 

 cow-wheat. Others again, after the seedling state, derive the 

 whole of their food from the host plant, and in these cases the 

 leaves which they bear, being diverted from their true functions, 

 are reduced to scales, so that the parasite degenerates into a bundle 

 of reproductive organs with the stems which are necessary to 

 support the flowers and to convey nourishment to the parts which 

 require it. Examples of these are furnished by the dodder, broom- 

 rape, and toothwort. 



The Saproplii/tes, which are closely allied to the Parasites, and 

 some of which were formerly regardeil as belonging to them, obtain 

 their nourishment from decayed vegetation. Their usual habitat 

 is under trees where the accumulated leaves of many seasons have 

 formed a considerable depth of loose soil. One genus at least, 

 Monotropa, has no roots, being reduced to stem, leaf, scales, and 



