174: THE FERTILISATION OF FLOWERS. [PART 111. 
Tribe T7rifolie. 
92. ONONIS sSPINOSA, L.—This plant also has flowers with a 
piston-mechanism, which however differ materially both from Lotus 
and Anthyllis. They are devoid of honey, and, like almost all the 
honeyless Papilionacez, monadelphous, for the separation of the 
superior stamen in other forms is only useful in giving access to the 
honey. The ale, which serve as in most other Papilionaceze for 
bees to alight on, and as levers to depress the carina, embrace the 
upper part of the carina (3, Fig. 55) and are united to it by two 
projections directed downwards and forwards (5d), which fit mto 
deep grooves in the two halves of the carina. Two lobes at the 
base of the upper borders of the ale (3, 6, ¢) directed backwards, 
but not pouched, lie over the staminal column without touching it, 
Fic. 55.— Ononis spinosa, L. 
1,— Essential organs from a bud. 
2.—Ditto, from a flower (x 7). 
3.—Flower, from the side, after removal of calyx and vexillum. ; 
4.—Some stamens, more magnified, to show the difference between the outer and inner filaments. 
5.—Left ala, from the inside. 
6.— Ditto, from the outside. 
a, outer, b, inner stamen ;c, pollen, seen through the carina; d, alar processes pointing down- 
wards and forwards ; e, lobe of the upper border of the ala, pointing backwards, 
and can give little help in keeping the parts in their proper places. 
The two alze never cohere with one another. 
The upper borders of the carina cohere at first, leaving a small 
opening at the tip, and the pollen is squeezed out as in Lotus. But 
sooner or later after repeated depressions this suture ruptures, and 
now if the carina be depressed the anthers themselves emerge. Ifthe 
carina was not thrust down too far they return within the carina 
when the pressure is relieved ; but if the carina was pressed violently 
down, as it frequently is by bees, the anthers remain along with the 
stigma partly or wholly exposed, | 
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