parvum] § THE MECHANISMS OF FLOWERS. 299 
| Weigelia (Diervilla) rosea, L.—The flower is adapted for bees, 
and undergoes a change of colour after fertilisation like Ribes 
aurewm (590, III.). 
REVIEW OF THE CAPRIFOLIACEX. 
The small group of Caprifoliacew is remarkable for the great 
variety of visitor’ to which nearly related plants have adapted 
_ themselves, chiefly by differences in the length of the tube. 
 Lonicera Caprifolium, L., with a tube about 30 mm. long, permits 
_ only a few Lepidoptera to reach the honey; LZ. Periclymenum, L., 
_ in which the tube is only 20 mm. long, admits also a few specially 
_ long-tongued bees ; LZ. cwrulea, L., with a pendulous corolla and a 
_ tube over 10 mm. long, is adapted for humble-bees ; in Z. tatarica, 
| L,, and L. Xylostewm, L., the length of the tube falls to 7 to 3 mm, 
and certain long-tongued flies, in addition to a larger company 
_ of bees, visit and fertilise the flowers; the short, wide honey- 
_ receptacles of Symphoricarpos and Ledasione alpigena, L., are easily 
accessible even to wasps, which are attracted in great numbers by 
the large supply of honey ; Linnea is farnished with an infundi- 
-buliform corolla, but apparently attracts, for the most part, flies ; in 
Viburnum the honey is freely exposed, but only as a flat, adherent 
layer, and the plant is visited chiefly by short-lipped insects, e.g. 
flies and beetles; Sambucus attracts a similar set of insects, which 
are less varied and fewer in number owing to the absence of 
honey; Adoxa attracts only minute honey-seeking insects. In 
case of insect-visits, cross-fertilisation is insured in all, but in very 
_ various ways; self-fertilisation in the absence of insects is rendered 
possible in those species which are least visited. In the least 
; specialised and most generally accessible Caprifoliaceze (Adoxa, 
i Sambucus, &c.) the flowers are white or greenish; in those species 
fertilised by wasps they are reddish (Symphoricarpos) or reddish- 
‘ brown (Lonicera alpigena, L.); in several species of Lonicera fer- 
 tilised by bees (eg. Z. tatarica) they are bright red, in LZ. cwrulea 
_ they are yellowish-white, but they are pale in those species which 
have the longest tubes and are adapted for crepuscular Lepidoptera 
(L. Perichymenaini, L. Caprifolium). 
