Chapter VIII 



DROSOPHYLLUM LUSITANICUM 



Drosophyllum lusilanicum Lk. (jj — 2) is a plant with much the ap- 

 pearance of Byblis, but it is larger and shrubbier (1-1.6 m. tall) and is 

 unusual, for the carnivorous plants, in growing not in a wet, but in a 

 very dry habitat in Morocco and nearby Portugal and Spain. Harsh- 

 BERGER visited a locahty in Sra. de Valongo near Oporto, where he 

 found Drosophyllum growing in open formations, scattered over the 

 quartz-rocky soil. He observed its leaves to be crowded with small 

 gnats. Its flowers are bright sulphur yellow, are i-i>^ inches in 

 diameter, and have convolute aestivation. It is called locally "herba 

 piniera orvalhada" (dewy pine) in allusion to its bedewed appearance 

 due to the numerous glands carrying large droplets of clear mucilage. 

 The base is strongly woody, and its abundant roots penetrate deeply 

 into the dry soil. "Mr. W. C. Tait informs me that it grows plenti- 

 fully on the sides of dry hills near Oporto, and that vast numbers of 

 flies adhere to the leaves. The latter fact is well known to the vil- 

 lagers, who call the plant the 'fly-catcher,' and hang it up in their 

 cottages for this purpose" wrote Darwin (1875). Inquiry by corre- 

 spondence with Dr. QuiNTANiLHA has elicited doubt of the correctness 

 of Tait's statement as to the use by the paisanos of the plant as a 

 fly-catcher, though it seems reasonable enough. 



The leaf is linear with a deep furrow along the upper side. It 

 is traversed by three vascular bundles, a median and two lateral, arising 

 from a single bundle entering at the base {14 — 5). 



A peculiar feature is found in the reverse circination (14 — 4) the 

 rolled leaf-tip facing outwardly while in Drosera very generally the 

 opposite holds. Although in Byblis gigantea the leaves are nearly 

 straight, showing no evident circination, in Byblis linifolia the be- 

 havior is like that of Drosophyllum. Fenner expresses the opinion 

 that this arrangement has its significance in permitting the free de- 

 velopment of the stalked glands, but he overlooks the fact that the 

 circination of Drosera is in the opposite sense without any prejudice 

 to the development of the tentacles. The case of Byblis linifolia was 

 not known to him. In any event, in the tight coils the dorsal and 

 ventral leaf surfaces are mutually compressed; and assuming that the 

 tentacles (hairs in the case of Byblis) develop after uncoiling, the ven- 

 tral (upper) surface is freer than the dorsal, where the most of the 

 tentacles or hairs are to be found. 



Another characteristic behavior of the leaves is their marcescence. 

 Instead of falling away as they die, they remain attached, forming a 

 grass-skirt about the stem. Franca (1922) regarded this as a symptom 

 of a condition which he regarded as pathological, due to overnutrition 

 and the inability, because of the absence of an excretory apparatus, to 

 throw off waste. Quintanilha, however, disagrees with this and, in 

 our opinion, justly. 



