Chapter IX 

 PINGUICULA, BUTTERWORT 



Distribution. — General appearance. — Habitat. — The leaves. — Two kinds of glands 

 (Points of structure. Early work of Darwin: movements. Secretion and digestion). — 

 Popular uses. 



The genus Pinguicula consists of about 30 species distributed 

 throughout the northern hemisphere in temperate or cool temperate 

 regions. Although making use of a far different mode of capture of prey, 

 it is closely related to Utricularia and Genlisea, and is one of the three 

 lentibulariaceous genera, as shown by the flower structure. The 

 personate corolla is blue, purple or yellow, and differs from that of 

 Utricularia principally in the five-parted cal30c. 



All the species are of very uniform character. The plant consists 

 of a short vertical stem giving rise to a compact rosette of leaves which 

 usually lie flat on the ground, or in some species {P. gypsicola) are 

 directed obHquely upward also. They exhale a distinct fungus-like 

 odor. The tissue tensions in the leaves are such that when a plant is 

 uprooted from the soil they become at once strongly reflexed, as 

 Darwin observed; but this is a feature common to rosette plants. 

 The leaves are entire, usually ovate {P. vulgaris) or broadly ovate {P. 

 cuneata), with upcurled margins. In color they are a pale faded green, 

 yellowish in bright light (Batalin), deeper green in the shade, in P. 

 vulgaris pale purple due to the presence of pigment in the lower epider- 

 mis. They are very soft and yielding, easily bruised and torn; and, 

 being "greasy" to touch, the name, derived from the Latin pinguis, 

 fat, was suggested, according to accounts. The dorsal surface is quite 

 smooth and shiny, the ventral ghstening with myriads of minute 

 mucilage glands. In addition to their glands, both surfaces bear num- 

 erous stomata peculiar in having no chlorophyfl, though there is pres- 

 ent according to Batalin a pale yellow pigment. The flowers are 

 borne singly on slender, glandular, pubescent scapes, have a five-parted 

 corolla, with a slender spur, so large and showy in some species of the 

 genus that they are found in glasshouse cultivation. Although the 

 peduncles also have glandular hairs, Darwin thought them devoid 

 of digestive function. The seedlings have a short taproot possessed 

 of a few root hairs, but this does not persist and soon gives way to 

 adventitious roots arising from the stem above. In possessing a tap- 

 root, even though fugacious, this genus differs from the others of the 

 family, in which there is none. There is but one cotyledon, which 

 arises as a semicircular ridge around the plumule, and when fully 

 developed is strongly folded lengthwise and may in longitudinal 

 sections be easily interpreted as two, as Goebel pointed out. 



Pinguicula grows in wet places, with mosses, etc., in chinks of wet, 

 dripping rocks, on hummocks in swamps {ij — 4) and similar situa- 

 tions, in general conformity with the majority of carnivorous plants. 

 Towards the end of the growing season the plant produces very com- 



