250 THE FERTILISATION OF FLOWERS. © [parr ill. 
159. Rrpes nigrum, L.—The stigma and anthers are both — 
alike ripe at the opening of the flowers. The anthers open on the 
inner side, and are brought so close to the stigma by the conver- — 
gence of the petals that an insect’s head, when pushed into the 
flower, must touch with one side the pollen-dusted face of one or 
two anthers, and with the other, at the same time 
or a little before, the slightly protruding stigma. 
Since the bell-shaped calyx, whose floor secretes 
honey, is 5 mm. deep, and the red tips of the 
sepals and the small white petals make the pendu- 
lous flowers only slightly conspicuous, insect-visits 
are not plentiful: I have only seen the honey- 
bee sucking at this species. It put its head only 
once into each flower, and touched the stigma now 
on the upper side, now on the lower, sweeping 
away pollen each time on the opposite side and so regularly ac- 
complishing cross-fertilisation. As compensation for the paucity of 
insect-visits, self-fertilisation takes place regularly in unvisited 
Fic. 82.—Ribes nigrum, 
L. 
Lateral view of flower. 
flowers, pollen falling of itself out of the anthers upon the recurved 
margin of the stigma. 
160. RIBES RUBRUM, L., is likewise homogamic, but has much 
flatter, more widely open, and more conspicuous flowers than 
R. nigrum, and more easily accessible honey. So it is more 
abundantly visited by insects, and is cross-fertilised after the same 
manner as &. nigrum but is self-fertilised less easily; the flowers — 
are turned sideways, and self-fertilisation only takes place when ~ 
pollen falls upon the stigma from the anthers above it. I have 
seen the following insects upon the flowers :— 
Hymenoptera—(a) Apidae; Andrena fulva, Schrank, ?, s. and ¢.p., freq. ; 
(2) A. Smithella, K. ¢, s.; (3) A. nana, K. ¢, s.; (4) Apis mellifica, L., ~ 
%, 8. and cp., ab. ; (b) Tenthredinide: (5) Nematus hortensis, Htg,, s. 
161. Rises GrossuLariA, L.—The anthers dehisce when 
the flower opens: the styles have not as yet attained their full 
length, nor have the stigmas developed their papillae. Since the 
flowers mostly hang down perpendicularly and the stamens stand 
around, and on a level with, the stigmas, self-fertilisation can as a- 
rule not take place, even in default of insect-visits. This, like the 
proterandry, points to more numerous insect-visits than the former — 
species receives ; and these really take place, induced by the large 
recurved sepals, the large, perpendicular, downward-pointing petals, 
and the easily accessible honey. 
| 
: 
