VIOLACEAE 
607 
sometimes occur. The flrs. stand usually one in each axil ; sometimes 
( e.g . V. tricolor -) a vegetative shoot arises above the fir. in the same 
axil. The chief interest centres in the firs. The introrse anthers 
form a close ring round the ovary, below the style, which ends in a 
variously shaped head on whose anterior surface is the stigma, often 
a hollow pocket. The lower petal forms a landing-place and is often 
prolonged backwards into a spur, in which collects honey, secreted by 
processes projecting into it from the lower sta. These firs, are as a rule 
incapable of self-fertilisation. In V. tricolor the pollen is shed on to 
the anterior petal, and the lower edge of the stigma is guarded by a 
flap which the insect, when withdrawing, closes ; and thus the flower’s 
own pollen is prevented from reaching the stigma. The small-flowered 
subspecies V. arvensis Murr. has not this flap and fertilises itself. In 
V. odorata the stigma is merely the bent-over end of the style, and is 
first touched as the insect enters. The size, colour, &c., of the flower 
of this sp. and of V. canina render them adapted to bees. 
In many sp., e.g. V. canina , V. odorata , V. sylvesti'is Lam., the flrs. 
are but rarely visited, and very little seed is set. They usually flower early 
in the season; later on appears a second form of flr. on the same plant. 
These are the cleistogamic flrs., which never open, but set seed by 
self-fertilisation (see p. 98). In V. canina this flr. looks like a bud; 
the sepals remain shut, there are 5 very minute petals, 2 anterior sta. 
with anthers containing a little pollen (only just enough for fertilisa- 
tion — there is no waste as in open flrs.), and 3 other abortive sta. ; the 
pistil is much as usual. The anthers are closely appressed to the 
stigma; the pollen-grains germinate within them, and the tubes burrow 
through the anther-walls into the stigma. V. odorata has very similar 
flrs. , but with all 5 sta. fertile. The production of these flrs. ensures 
the setting of a fair amount of seed. Their appearance is partly 
dependent on shade (they are always well shaded by the leaves &c.), 
for a reduction of the intensity of the light causes the plant to produce 
cleistogamic flrs. only (see Vochting in Prmgs. Jahrb. 1893). It is 
however likely that other factors (cold, degree of moisture, soil &c.) 
also affect the result; and the prduction of these flrs. is apparently 
hereditary though very variable. 
The fruit is a 3-valved capsule ; the seeds are very hard and slip- 
pery. One placenta with its seeds remains attached to each valve ; 
as this dries it bends upwards into a U -shape, squeezing the seeds 
against one another and shooting them out (see p. hi, and cf. Clay- 
tonia, Buxus). 
Violaceae. Dicotyledons (Archichl. Parietales). 15 gen. with 300 sp. 
cosmop. Annual or perennial herbs, or shrubs. Leaves alt., stipu- 
late, usually undivided. Firs. 1 or 2 in each axil, in usually racemose 
infls., bracteolate, £ , usually zygomorphic. K 5, persistent ; C 5, hypo- 
gynous, usually zygomorphic, the anterior petal often spurred to hold 
the honey, with descending aestivation; A 5, alt. with petals, hypo- 
