LEG UMINOSAE 
435 
fertilisation exists. Self-pollination usually occurs when the insect 
flies off, leaving the keel to return to its former position. 
‘ ‘ Four different types of structure may be distinguished (in Papilio- 
natae) according to the manner in which the pollen is applied to 
the bee: (i) P. in which the sta. and stigma emerge from the carina 
and again return within it. They admit repeated visits ; e.g. Tri- 
folium, Onobrychis. (2) P. whose essential organs are confined under 
tension and explode. In these only one insect’s visit is effective ; 
e.g. Medicago, Genista, Ulex. (3) P. with a piston mechanism 
which squeezes the pollen in small quantities out of the apex 
of the carina, and not only permits but requires numerous insect 
visits ; e.g. Lotus, Ononis, Lupinus. (4) P. with a brush of hairs 
upon the style which sweeps the pollen in small portions out of the 
apex of the carina. They for the most part require repeated insect 
visits ; e.g. Lathyrus, Vicia.” (Muller.) Cleistogamy is fairly common 
in the order. In several cases the stigma in the unvisited flr. lies in 
the keel among the pollen, but it has been shown that it only becomes 
receptive (if young) when rubbed, so that autogamy does not neces- 
sarily occur in these cases. The first visitor will rub the stigma and 
autogamy will of course occur then, but if there were any other pollen 
on the insect, a cross will happen. For the peculiar phenomenon of 
enantiostyly (right- and left-styled firs.) see Cassia. Some sp. have 
firs, which after fertilisation bury themselves in the earth and there 
ripen their fruit; e.g. Arachis, Voandzeia, Trifolium, Vicia, La- 
thyrus, &c. 
The fruit of the L. is typically a legume or pod opening by both 
sutures. In some the pod is constricted between the seeds, forming 
a lome 7 itu?n which breaks up into indehiscent one-seeded portions. 
The pods frequently open explosively, the valves twisting up spirally, 
e.g. in Ulex, Cytisus sp., &c. In Colutea, &c. the pods are inflated 
and so catch the wind. Others are winged. Some are eaten by 
animals* but the seed-coats are hard enough to preserve the seeds 
from injury. Some have a coloured fleshy aril (Acacia sp., &c.). 
Still others have hooked pods, e.g . Medicago, Mimosa. [See Buch- 
wald in Engler’s Bot. Jahrb. XIX. 1894.] 
The seed is exalbuminous and contains as a rule a very large 
store of reserve-materials in the cotyledons. This is of great import- 
ance to the young plant (p. 112), and in this respect the L. are better 
provided than most other families. 
Economically the L. is a most important order. The seeds of 
many sp. form important food-stufls, e.g. of Arachis, Cajanus, Cicer, 
Dolichos, Glycine, Lathyrus, Lens, Lotus, Lupinus, Phaseolus, Pi- 
sum, Vicia, Voandzeia, &c. The pods of Ceratonia, Tamarindus, 
Phaseolus, Prosopis, &c. are also eaten. A great number are valuable 
as fodder plants, e.g. Trifolium, Medicago, Onobrychis, Lotus, Vicia, 
&c. Many tropical sp. yield valuable timber ; Crotalaria and others 
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