94 ANGIOSPERMAE—DICOTYLEDONES 



ones are absent. Kerner noticed slight protogyn}'. Warnstorf describes this plant as 

 being homogamous at Ruppin. Hermaphrodite flowers and flowers with aborted 

 stamens are there found on the same plants, i. e. the plants are gyno-monoecious. 

 The pistil of the female flowers is bilateral and reddish-brown. The pollen-grains 

 are whitish, ovoid or ellipsoid, finely granulated, about 30 /x long and 25 /x broad. 



Visitors. — Hermann Miiller observed the following. — 



A. Coleoptera. [a) Cur culionidae : i. Centorhynchus sp. (1^) Mordellidae: 

 2. Anaspisrufilabris (^_>'//. \c)Nitidulidae: ■>,.M.t\\%t\h.fi,. B. Diptera. {a) Empidae: 

 4. Empis vernalis Mg., sk,?. {b) Syrphidae : 5. Ascia podagrica F., po-dvg. ; 6. 

 Rhingia rostrata Z., skg. C. Hymenoptera. Apidae : Apis mellifica L. 5, skg. 



MacLeod noticed a Muscid in Flanders (Bot. Jaarb. Dodonaea, Ghent, vi, 1894, 

 p. 200). 



In Dumfriesshire a hover-fly was recorded (Scott-Elliot, ' Flora of Dumfriesshire,' 

 p. 12). 



61. Hugueninia Reichb. 



220. H. tanacetifolia Reichb. ( = Sisymbrium tanacetifolium L.). — 

 Flowers homogamous, and smell like honey. Briquet (' Etudes d. biol. flor. 

 d. les Alpes Occident.') says that their diameter is 5 mm. The calyx and 

 the yellow corolla are spreading. The stamens diverge and turn their anthers 

 horizontally with the dehisced side directed upwards. Kirchner adds that in the 

 Botanic Garden at Hohenheim, both petals and stamens are erect, so that the 

 stigma is closely enveloped by the four upper anthers, and automatically self- 

 pollinated. According to Hildebrand (Ber. D. bot. Ges., Berlin, xiv, 1896), the 

 plant is self-sterile. 



Visitors. — Briquet states that these are flies, wasps, bees, and Lepidoptera, 

 which chiefly eflfect self-pollination. 



62. AUiaria Adans. 



Small white homogamous flowers, with half-concealed nectar. There are four 

 nectaries, but only the two at the bases of the short stamens are functional — 

 secreting on their inner sides. The two others — between the bases of the long 

 stamens of each pair — do not secrete. 



221. A. officinalis Andrz. (= Sisymbrium AUiaria Scop.). (Herm. Miiller, 

 'Fertilisation,' p. 109, ' Weit. Beob.,' H, p. 202; MacLeod, Bot. Jaarb. Dodonaea, 

 Ghent, vi, 1894, p. 199; Knuth, ' Bliitenbiol. Herbstbeob.') — The nectar secreted 

 by the functional nectaries at first forms four drops at the base of the flower between 

 the short stamens and the adjacent long ones, and ultimately fills the space 

 between the bases of the stamens and pistil. As the nectar is secreted inwards, 

 and not towards the sepals, the latter are superfluous after the flower has opened, 

 and readily fall away. All the anthers dehisce introrsely, and those of the long 

 stamens so closely surround the stigma that automatic self-pollination must take 

 place, and according to Hildebrand this is effective (Ber. D. bot. Ges., Berlin, xiv, 

 1896). Insects, when probing for nectar or devouring or collecting pollen, must 

 sometimes effect cross-pollination owing to the relative position of the anthers 

 and stigma. 



