CRUCIFERAE 89 



204. C. resedifolia L. — Schulz ('Beitrage,' II, pp. 13-14) says that automatic 

 self-pollination is inevitable in the homogamous flowers. 



Visitors. — Herm. Miiller saw 6 flies (Muscidae, Syrphidae, Empidae) and 

 a butterfly in the Alps. 



205. C. alpina L. — According to Kemer this species is protogynous. The 

 stigma projects from the opening flower, the stamens being still immature, so that 

 at this stage pollination can only be effected by the agency of insects. Automatic 

 self-pollination is possible later on when the stamens elongate. 



206. C. chenopodifolia L. — Grisebach states that in this species there are 

 subterranean cleistogamous flowers in addition to the open flowers above ground. 



56. Dentaria Toum. 



Flowers of considerable size, whitish or reddish, usually with concealed nectar. 

 As a rule there are four nectaries. 



207. D. enneaphylla L. (Schulz, 'Beitrage,' II, p. 14.) — The whitish-yellow 

 petals are 13-17 mm. long. Outside the base of each short stamen there is 

 a crescentic outwardly directed ridge, and at the middle of the bases of each pair 

 of long stamens a broad process projecting upwards. These four nectaries secrete 

 an insignificant amount of nectar. The anthers of the long stamens usually project 

 a little above the petals, and are generally at the same level as the stigma — which is 

 frequently mature before anthesis — though in rare cases they are a little lower. As 

 even in warm weather the petals and stamens diverge but little, the anthers are so 

 near the stigma that automatic self-pollination necessarily takes place. The anthers 

 of the short stamens usually reach only to the middle of the long ones, and dehisce 

 at the same time as, or a little later than, the anthers of these. They serve exclusively 

 for cross-pollination. 



Visitors. — Schulz — at Sanmartino and Paneveggio — saw flies and beetles and 

 especially Noctuidae creeping into the flowers. 



208. D. bulbifera L. (Kirchner, 'Flora v. Stuttgart,' p. 291; Knuth, 'Bloe- 

 menbiol. Bijdragen.') — In the large pale lilac, rose-red, or white flowers, there is 

 a nectary outside the base of each short stamen, and one that is usually cleft outside 

 the insertions of the two pairs of long stamens. Sometimes the four nectaries unite 

 to form a ring. Fruits are found only in sunny places where insects visit the flowers ; 

 in shady woods the plant is almost always sterile, propagating by dark-violet bulbils 

 produced in the axils of the leaves. 



Visitors. — In spite of much watching I have never seen insects visiting the 

 flowers in the woods near Kiel and Flensburg, and have very rarely noticed fruits. 



57. Hesperis L. 



The odorous flowers are of considerable size, and their nectar is concealed. 

 They belong to the flower-classes C and L. 



209. H. matronalis L. (Herm. Miiller, 'Fertilisation,' pp. 108-9; Kirchner, 

 ' Flora V. Stuttgart,' p. 293 ; Warnstorf, Verb. bot. Ver., Berlin, xxxviii, 1896 ; Kemer, 

 ' Nat. Hist. PI.,' Eng. Ed. i, II, p. 209; Knuth, 'Weit. Beob. u. Bl. u. Insekt. a. d. 



