496 THE FERTILISATION OF FLOWERS, [PART IIT. 
Lamium amplexicaule, L. (see Fig. 2, p. 19).—The tube is 14 to 
16 mm. long, narrow for the lower 10 to 11 mm., and above that wide 
enough to admit a humble-bee’s head. I have never seen the 
flowers visited by insects, though they are no doubt cross-fertilised 
by humble-bees; but I have often found, immediately after the 
opening of the flower, the tip of the lower stigma standing not 
above but below and between the anthers, and dusted with pollen, 
—no doubt, from the same flower. Besides these normal self- 
fertilising flowers, the plant reproduces itself by means of cleis- 
togamic flowers, These have been described minutely by Walz 
(759) and Hildebrand (351). 
360. LAMIUM GALEOBDOLON, Crantz—The tube is 8 mm. 
Jong, smooth in its lower, honey-holding part, but lined with hairs 
above ; the entrance is expanded, and the hive-bee can reach the 
base of the flower though its proboscis is only 6 mm. long. The two 
branches of the style are beset with very short, flat papillae which 
do not increase in size, and they diverge almost to their full extent 
soon after the flower opens. Cross-fertilisation is favoured not by 
dichogamy but by the position of the parts. At first the tip of the 
lower division of the style lies somewhat above the lower surface 
of the anthers, and hence if the bee's back presses lightly against 
the anthers it escapes being touched; if the bee is large and 
presses forcibly against the anthers, the stigma at least comes in 
contact with a different part of the bee, and is more likely to re- 
ceive pollen from another flower than its own. Afterwards the tip 
of the lower stigma comes to project below the anthers, and is 
now regularly touched first by the bees. I have observed, 
on plants kept in the house, that, in the absence of insects, 
pollen usually falls in the course of time upon the lower 
stigma. 
The visitors are exclusively bees. 
(1) Bombus hortorum, L. 9 (21), ab. ; (2) B. silvarum, L. 9 (12—14) ; 
(3) B. Rajellus, Il. 9 (12—13); (4) B. agrorum, F. 9 (13—15), very freq. : 
(5) B. pratorum, L. § 9 (8—12), ab., all sucking normally, and sometimes 
brushing the pollen from their backs into their pollen-baskets ; (6) B. terres- 
tris, L. 9 (7—9), boring holes to suck, though its proboscis is long enough to 
reach the honey in a legitimate manner ; (7) Apis mellifica, L. 8, usually 4 
takes advantage of the holes bored by B. terrestris,—once I found it sucking 
in the normal way, with its back thickly covered with pollen. See also No, | 
590, 111., and No, 609, 
361. LAMIUM MACULATUM, L., agrees in the main features of 
its flower with Z. album; but its tube is 15 to 17 mm, long, so 
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