DROSERA 
366 
fluid that glistens in the sun like dew. Flies and other insects mis- 
taking it for honey are held by it. The tentacles are exceedingly 
sensitive to continued pressure even by the lightest bodies ; the result 
is to cause an inward and downward movement of the head of the 
tentacle, finally placing the fly upon the blade of the leaf. At the 
same time the stimulus passes to the surrounding tentacles causing 
them also to bend downwards to the same point. The victim is thus 
smothered and now the glandular heads of the tentacles secrete a 
ferment which acts upon the proteids of the insect and brings them 
into solution, when they are taken up by the leaf. Afterwards the 
tentacles expand once more and recommence the secretion of the 
sticky fluid. It has been shown by direct experiment that the food 
thus obtained is of great benefit to the plant, though it can live without 
it. By this means D. is able to live in very poor soil where no other 
flowering plants can live. It is noteworthy that the extra materials 
thus obtained are devoted chiefly to seed-production. If the stimulus 
produced by the capture of an insect be very powerful, the leaf itself 
may bend into a cup form, and this feature is very marked in some sp., 
the leaves bending almost double over the prey. [See p. 178-] 
The firs, of the Brit. sp. rarely open, but pollinate themselves in 
the bud. The stigmas are branched each into two lobes. 
Droseraceae. Dicotyledons (Archichl. Sarraceniales) . 6 gen. with 100 
sp. Drosera is a cosmopolitan genus, the rest are more local in distri- 
bution. Herbaceous plants, usually with perennial rhizome and 
rosettes of leaves. Aldro vanda is a water-plant. All are insectivorous 
plants; Dionaea and Aldrovanda have sensitive leaves which shut up 
when touched, the others catch their prey by means of sticky tentacles 
upon the leaves. For details see individual genera. Firs, usually in 
cincinni, rarely in racemes or solitary, £ , regular, 5 — 4-merous, usually 
hypogynous. K (5) ; C 5, imbricate or convolute ; A usually 5, pollen 
in tetrads (cf. Ericaceae). Cpls. 2, 3 or 5, united; placentae usually 
parietal, rarely axile or free-central; style long; stigmas simple or 
branched. Ovules 3 — 00 , anatropous. Loculicidal capsule. Seed 
with endosperm and small basal embryo. Genera : Dionaea, Aldro- 
vanda, Drosophyllum, Drosera, Byblis, Roridula. Placed in Rosales 
by Benth.-Hooker, in Cistiflorae by Warming. 
Drosophyllum Link. Droseraceae. 1 sp., D . lusitanicum Link, Morocco, 
Portugal, S. Spain. The long narrow leaves are provided with 
glands of two kinds— stalked glands secreting a sticky fluid (cf. 
Drosera), and sessile ones which only secrete when stimulated by 
nitrogenous matter, and then secrete a digestive ferment. Insects 
alight on the glands and are entangled by the sticky secretion ; they 
struggle for a while and finally sink down and die upon the leaf and 
are digested by the ferment. The taller glands have no power of 
movement, but are able to secrete a ferment as well as the sessile ones. 
[See p. 178 and Bot. Cent . 60, p. 33 ] 
