Francis E. Lloyd — 116 ^ Carnivorous Plants 



points out the absence of data on the nitrogen content, and cites, in 

 order to fill the gap, the fact, stated by Wollny (1897), that the soil 

 (raw humus) of a pine forest as compared with that of the Drosera 

 habitat, contains nitrogen in the proportion of 27:1. Even more strik- 

 ing than the fact that the habitat is of such poor quality in respect to 

 salt content is the further observation that the first immigrants onto 

 the newly cut turf surfaces after the removal of peats, is Drosera, and 

 this remains for a long time the only inhabitant of these raw peat 

 surfaces. We may recall in this connection that Correns (1896) 

 showed that tap water at a high temperature (54.4° C.) does not 

 cause movements of the tentacles, but that water devoid of CaCOs 

 and CO2 called forth reactions at that temperature. In this way he 

 detected a toxic effect of Ca and inferred that this substance in the 

 soil (at least too much of it) might be toxic. 



Form and habit of the plant. — The commonest type of Drosera 

 consists of a slender stem crowned by a rosette of leaves with flowering 

 scapes growing in the leaf axils. It arises from a seedling (D. rotundi- 

 folia) which has a fugacious taproot, which, however, serves for the 

 formation of the earliest rosette of leaves (Nitschke, i860). Ac- 

 cording to Heinricher (1902) the taproot fails to elongate, but swells 

 into a rounded mass covered with root hairs. The cotyledons are 

 simple, spatulate, followed by leaves of the mature type, though small 

 and with fewer appendages (tentacles) than the latter. As the plant 

 grows the stem dies off behind. In winter the rosette is reduced to a 

 tight compact winter bud which may have no extending stem or roots. 



Growing as it {D. rot^indifolia e.g.) does in mats of Sphagnum, the 

 differential growth rates of these plants brings it about that Sphagnum 

 by its more rapid growth during the cool months, overtops the Drosera 

 and in the warmer months the latter in its turn overtops the Sphagnum. 

 One sees, therefore, in a Drosera plant, which has grown in this way, 

 successive dead rosettes clinging to the dead stem, ending above in a 

 living rosette, as figured by Nitschke. Such are our familiar species 

 of the northern hemisphere. The leaves of the rosette when fully ex- 

 panded may be relatively small, as in D. rotundifolia, intermedia, etc., 

 or very large and ligulate, as in a remarkable species, D. regina, de- 

 scribed by Miss E. L. Stephens from S. Africa. In this species the 

 leaves are 2 cm. broad by 35 cm. long. Or again the leaves may be 

 large and fern-like in aspect, with strong terete petioles with a once to 

 thrice parted leaf blade as in D. binata, D. dichotoma (S. Africa, Aus- 

 tralia). These make showy greenhouse plants, and have often been 

 cultivated and used for study, to be reported upon in some detail 

 beyond. 



Or again the main stem may be elongated upward, only slightly in 

 D. capensis, an often cultivated form from S. Africa, with hgulate leaf 

 blades supported on rather long petioles {13 — 5,7). In the most stately 

 species D. gigantea the stem may be a meter long and many plants together 

 form a dense half shrubby tangle crowned with the numerous flowers 

 in panicles. The stems climb or clamber, partly by twisting and partly 

 by means of certain long-petioled leaves in which the leaf blade be- 

 comes a disc of attachment, its dense secretion forming an adhesive 

 (GoEBEL 1923). The stems are wiry, the leaves peltate and deeply 

 cupped. It is a pronounced sclerophyll, according to Czaja. 



