i 
230 THE FERTILISATION OF FLOWERS. [PART II. 
with hermaphrodite proterogynous flowers, other plants occur in 
all of whose flowers the pistil is suppressed while the stamens 
remain (609). 
137. GEUM uRBANUM, L.—The flowers are much smaller than 
those of G. rivale, and appear at a season (July, August) and in 
spots where many more conspicuous flowers compete with them. 
They accordingly receive few insect-visits, and rely for the most 
part on self-fertilisation. 
Honey is secreted by a green, fleshy, annular ridge at the 
base of the receptacular tube, internal to the insertion of the 
stamens. When the flower opens all the stamens are bent inwards, 
so that their anthers lie close upon the outer carpels, while the 
inner styles with ripe stigmas project in the centre of the flower. 
The outermost stamens now bend outwards and the anthers dehisce, 
turning their pollen-covered surfaces upwards; when the innermost 
stamens dehisce in their turn, some of their pollen almost always 
comes upon the outer stigmas. If the flower is visited early by — 
insects, its feebly-marked proterogynous dichogamy may insure 
cross-fertilisation ; if the visits are deferred till later, crossing may 
still be effected by an insect which alights, dusted with pollen, 
in the centre of the flower. But self-fertilisation must take place 
very often, both spontaneously and by the agency of insects which 
alight at the edge of the flower. 
I have only observed the following visitors: A. Diptera—Syrphide : (1) 
Melithreptus scriptus, L., s. and f.p. B, Coleoptera—Dermestide : (2) Byturus 
fumatus, L., f.p. 
138. FRAGARIA VESCA, L. (Strawberry).—The honey is secreted — 
by a narrow, fleshy ring at the base of the receptacular tube, — 
sheltered between the stamens and the outer carpels. The petals 
spread out into a level disk, forming a convenient alighting-place 
for insects, An insect standing on a petal must, to reach the 
honey, thrust its head between the stamens, and bring it in contact 
with the stigmas. If both stigmas and anthers ripened together 
self-fertilisation would thus be occasioned directly by the insects, 
but as a matter of fact the stamens come to maturity much later 
than the stigmas. Cross-fertilisation is also favoured by the shape — 
and manner of dehiscence of the anthers; for these are expanded 
into flat disks, so that the intervening spaces are so much narrowed 
that even Halictus and the smaller flies cannot reach the nectary 
with their heads, without rubbing against some of the anthers. The 
