Linnceafi Society. ^7 



After some remarks on the interest which attaches to the examina- 

 tion of remarkable exceptions to the general laws of structure in 

 vegetables, and especially as regards parasitic plants, whether crypto- 

 gamous or phsenogamous, Mr. Bowman relates some curious pecu- 

 liarities which in the last and present year he had detected in the 

 Latlircea squamarta. Having caused the flowering stems of a young 

 plant to be trenched round, detaching from the ash-tree under which 

 it grew the contiguous portions of root, the whole mass was insulated 

 and separated ; and then, by cautious agitation in a neighbouring 

 stream, the soil was washed away, and the roots and fibres of the 

 ash, together with the subterranean stems of the Lalhrcta, com- 

 pletely matted together, were left exposed ; and showed, that though 

 its base does not penetrate the stock as in Orobanche, yet it is truly 

 parasitical, all its forked fibres having minute tubercles by which they 

 attach themselves to the roots of the tree. 



It is remarkable, that instead of rising towards the surface, the 

 embryo stem takes a downward direction, till it comes to the roots 

 of the tree, when it spreads among them and fixey its tubers on them, 

 the flowering branches being the only parts that appear above the 

 surface. 



To show the nature of the parasitical connection, Mr. Bowman then 

 gives a full and minute description of the tubers and their connecting 

 fibres, which had hitherto escaped notice, illustrated with highly mag- 

 nified figures. The tubers seem to be succulent homogeneous sub- 

 stances, sending down from their surface a tap into the alburnum 

 of the roots of the tree, to which the parasite has become attached, 

 but never into the woody fibre. 



In treating of the tooth-shaped scales, from which the plant has been 

 by some called Dentaria sguamaria, and Toothwort, Mr. Bowman 

 mentions that, their real character being mistaken, they had been con- 

 sidered as roots, till Sir J. E. Smith latterly referred them to their true 

 character, of a subterranean herbage, The absence of green colour 

 in most plants that are parasitic on roots, Mr. Bowman ascribes not 

 merely to theirborrowed nutriment, but more especially to their hav- 

 ing no true leaves j all plants destitute of leaves furnished with pores 

 not being subject to the action of the atmosphere and of light. The 

 Lathrcea, however, thougii furnished with true leaves, has the pale 

 hue of the other parasites ; and this Mr. Bowman ascribes to the 

 functions of the leaves being performed in the total absence of light, 

 and to their being destitute of pores.— The paper concludes with a 

 minute description of the curious structure of the subterranean leaves, 

 which appear to be furnished with cells lined with innumerable minute 

 glandular papillae, which Mr, Bowman supposes to perform the office 

 of cuticular absorbents. So that whereas ordinary leaves with a po- 

 rous cuticle, when acted on by air and light, receive carbonic acid gas, 

 and throwing oft the oxygen, retain the hydrogen and carbon ; in the 

 case of the La/Ar^a, whose leaves are buried, the air- valves, instead of 

 being in the cuticle, where they would have been obstructed by the 

 surrounding earth, are placed within the convoluted cells, which he 

 has discovered within the substance of the leaf. 



Dec. 1st. 



