LABIATAE 255 



reduced forms are set in motion by humble-bees, but, of course, uselessly for the 

 plant. In extreme cases the stamens are reduced to small lobes (Fig. 329). Correns 

 says that in these flowers with a small perianth the spoon-shaped parts of the con- 

 nectives are retained, while the rest of the anthers are reduced. It follows that not 

 only is the nectar protected from unbidden guests, but that bee visitors are compelled 

 to suck these smaller flowers in the same way as the larger ones, so that their stigmas 

 must be pollinated from the latter. Gynomonoecious as well as hermaphrodite and 

 female stocks are to be found. 



Schulz recognizes four forms occurring in Germany. 



(i) Large-flowered hermaphrodite form: corolla 27-29 mm. long; mouth 9-10 

 mm.; connectives 15-18 mm. ; pistil 32-42 mm. long. Protandrous or homogamous ; 

 in the latter case automatic self-pollination is possible, as the stigma is placed in the 

 line of fall of the pollen. This form is connected by transition stages with the 

 following : 



(2) Small-flowered hermaphrodite form: corolla 16-23 n^- loJ^gJ mouth 

 6-8 mm.; connective 8-16 mm.; pistil 25-35 mm. long. Usually homogamous, 

 or feebly, rarely markedly protandrous; automatic self-pollination is easily possible 

 when the style is long. 



(3) Large-flowered female form: corolla 19-24 mm. long; 6-7 mm. high; 

 pistil 28-34 mm.; connectives, on an average, 6 mm. long. The lever mechanism 

 is more or less reduced, the anthers sometimes normal, but devoid of mature pollen. 



(4) Small-flowered female form: corolla 10-15 "^' long, 5-6 mm. high; 

 connectives usually 3-4 mm. long, but sometimes entirely absent. Anthers minute. 

 Pistil 20-25 ^"^' loJ^g. often projecting far out of the flower, on account of the 

 smallness of the latter. 



Besides stocks bearing only these four forms, there are others with both female 

 and hermaphrodite flowers. The various forms grow either in different whorls, in 

 which case the female flowers are generally at the top of the inflorescence, or they are 

 arranged in whorls of three made up of mixed forms, of which the lateral ones 

 are female. Schulz found the flowers in the lower parts of the South Tyrol smaller 

 on an average than those in Germany ; here the length of the corolla varies usually 

 between 18-22 mm., the height of the flower entrance between 6-9 mm., the length 

 of the style between 23-36 mm. The size of the flower may sometimes be no more 

 than 12 or even 10 mm. The flowers in the lower parts of the South Tyrol are 

 feebly protandrous, partly homogamous. Automatic self-pollination is possible both 

 in flowers with a very short style and in those where this is considerably elongated, 

 the stigma in the first case coming into immediate contact with the anthers, while in 

 the second case it is brought into the line of fall of the pollen by the bending of the 

 style downwards. This possibility of automatic self-pollination is important for both 

 forms, since cross-pollination by insect-visits is not easily effected in either : in the 

 first case the stigma does not reach down to the visitor's back, and in the second it 

 generally touches that side of the insect not covered with pollen. 



In the higher districts of the South Tyrol the size of the flowers again increases. 

 Female stocks occur sporadically here, and in North Italy almost as frequently as 

 hermaphrodite ones ; gynomonoecious plants are also numerous. The size and form 

 of the nectaries are equally varied; in small hermaphrodite forms and in female 



