3IO 



ANGIOSPERMAEDICOTYLEDONES 



Cross-pollination is thus effected by insect-visits. (Hermann Miiller did not observe 

 automatic self-pollination ; Axell, however, says that it does occur and is effective.) 



In addition to hermaphrodite flowers, there are often female ones, according to 

 Schulz, up to 50 %, generally 10-20 %, and these are distributed partly gynomonoe- 

 ciously and partly gynodioeciously. Kirchner describes two forms of small-flowered 

 female stocks. In one case the corolla is of the normal form ; the stamens in the 

 usual position, but with white indehiscent anthers, and the style of the same length 

 as the upper lip. The other kind of female flower possesses stamens still further 

 reduced ; the lower lip is directed so far upwards that the entrance of the corolla is 

 only one mm. high ; and the stigma projects far beyond the upper lip. 



Besides large hermaphrodite flowers, MacLeod observed smaller ones (at Ghent), 

 which seemed to be almost cleistogamous and were self-fertilized. There were many 



intermediate stages between the two types. Purely 

 female flowers were not observed. 



Warnstorf describes three forms for Neu- 

 Ruppin. 



(i) Large flowers: corolla 15-16 mm. long 

 from the base of the tube to the tip of the upper 

 lip, entrance wide; corolla-tube longer than the 

 calyx ; lower lip strongly and irregularly dentate ; 

 hermaphrodite ; style generally of the same length 

 as the longer stamens ; autogamy effected by the 

 rolling up of the stigmatic branches ; pollen-grains 

 white in colour, ellipsoidal, tuberculate, about 

 50-56 /I long and 37-43 /* broad. 



(2) Medium-sized flowers : corolla 10-12 mm. 

 long, entrance wide ; style sometimes of the same 

 length as the longer stamens, sometimes a little 

 shorter ; sometimes hermaphrodite, with anthers partly reduced or entirely aborted. 



(3) Small flowers: corolla only 8 mm. long; lower lip curved inwards and 

 upper lip depressed, making the entrance of the flower very narrow ; style generally 

 shorter than the longer stamens ; hermaphrodite, or female by reduction of anthers. 



Stocks bearing large and medium-sized flowers predominate at Ruppin; the 

 small-flowered form seems to prefer the turf in gardens and parks. The keeled, 

 lateral teeth of the upper lip do not always grasp the lower, as described in Floras, 

 but often merely touch it. The order of development of the flowers is remarkable. 

 Of two neighbouring three-flowered half-whorls, the middle one of the upper and the 

 lateral ones of the lower open simultaneously, so that there are always three open 

 flowers near each other. (Warnstorf.) 



Visitors. Knuth observed the following bees. 



North Frisian Is., the honey-bee, and 3 humble-bees, skg. 1. Bombus rajellus 

 Kr, 2. B. lapidarius Z. ; 3. B. terrester Z., skg. Helgoland, the humble-bee 

 Bombus agrorum F. 5, skg. Thuringia, the short-tongued bee Halictus punctulatus 

 K. $, and 4 long-tongued humble-bees i. Bombus agrorum F.>^; 2. B. hortorum 

 Z., var. hortorum Z. ; 3. B. sorofensis F., var. proteus GersL 5 ; 4. B. terrester Z. 5 

 and 5. 



I 



Fig. 340. Prunella vulgaris, L. (after 

 Herm. Mailer), (i) Hermaphrodite flower, 

 seen from the front. (2) Upper part of 

 a longer stamen. (3) Do. of a shorter 

 stamen. 



