242 ANGIOSPERMAE—DICOTYLEDONES 



larger (diameter 14 mm.) than the female flowers, and have also, it seems to me, 

 a somewhat stronger odour, so that they are first visited by insects. 



Visitors. — In the Kiel Botanic Garden I observed on June 20, 1896, the honey- 

 bee, freq., skg., well dusted with pollen, and a hover-fly, Syritta pipiens Z., solitary, 

 po-dvg. and skg. 



At the close of his memoir (Jahrb. bot. Gart., Berlin, ii, 1883), Urban gives the 

 following summary of the flower mechanisms observed by him in the Rutaceae. — 



I. Plants Monoclinous. 



A. Flowers protandrous. 



I. The filaments bring the anthers one after the other to the place subsequently 

 occupied by the mature stigma, and afterwards return to their original position. 



(a) Style (and stigma) undeveloped during the male stage. 



(a) Ruta. The filaments are at first horizontal, then elongate considerably, 

 apply themselves to the ovary, again move back and become erect. Petals 

 horizontal. Self-pollination usually impossible. 



(/3) Coleonema. The filaments are at first short and erect ; they elongate, 

 bend over, and again become straight. Petals meeting together below 

 to form a tube. Automatic self-pollination possible by fall of pollen. 



(b) Style developed in the male stage (though sometimes imperfectly), but so 



placed that self-pollination is impossible. 



* Flowers zygomorphous. 



(a) Dictamnus. The filaments lie upon the under-lip ; they become curved, 

 the lower ones first, bend upwards over the middle of the flower, and 

 straighten again after shedding their pollen. The style is at first curved 

 somewhat downwards ; after the pollen has been shed, it bends upwards 

 at right angles. 



(/3) Calodendron. The filaments are curved upwards; they elongate, the 

 anterior ones first, and become almost straight before shedding their pollen, 

 finally curving outwards. The style, which is at first curved downwards, 

 straightens after the pollen is shed. 



* * Flowers actinomorphous. The filaments (successively) elongate considerably 



after dehiscence, 

 (a) Diosma. The style is at first curved horizontally over the ovary. The 



petals finally become erect, and the filaments curve outwards between them. 

 {p) Adenandra. As before, but the staminodes, not the petals, incline together 



at the end. The filaments of the fertile stamens curve outwards but Uttle. 

 (y) Barosma. The style curves outwards and downwards between the 



staminodes after the flower opens. The petals remain in a horizontal 



position, the staminodes are applied to the ovary, and the filaments of 



fertile stamens resume their original horizontal position after the pollen 



has been shed. 



