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LEGUMINOSAE 



Living in every soil and climate they show great variety in habit 

 trees, shrubs, herbs, water-plants, xerophytes, climbers, &c. The 

 roots of most exhibit peculiar tubercles metamorphosed lat. roots 

 containing peculiar bacterial organisms (Rhizobium sp.). Plants pro- 

 vided with these are able to take up much more atmospheric nitrogen. 

 The plant appears actually to consume the 'bacteroids' which live in 

 its cells, after they have stored up in themselves a considerable amount 

 of nitrogenous material. Hence the value of the L. as a crop on 

 poor soil, or as preceding wheat in the rotation of crops ; for instead 

 of impoverishing the soil they enrich it, either by the nitrogen con- 

 tained in their roots and liberated as these decay, or by that of the 

 whole pi. if ploughed in as 'green manure.' 



Stem commonly erect; many climbers. Some, e.g. Vicia, climb 

 by leaf-tendrils, some, e.g. Bauhinia, by stem-tendrils, some by hooks 

 (modified in Caesalpinia, &c., emergences in Acacia, &c.), some by 

 twining. Creeping stems, rooting at the nodes, also occur. Thorns, 

 usu. modified branches (e.g. Gleditschia) or stipules (Acacia), are 

 common. The stems of the erect trop. sp. often branch so that the 

 branches run parallel and erect, and bear crowns of 1. at the top. The 

 stems of many lianes are peculiarly shaped, often flat, or corrugated 

 in various ways, owing to peculiar growth in thickness. 



L. usually alt., slip., and nearly always cpd. Many have very small 

 1., e.g. Ulex, or scaly 1. and flat stems, e.g. Carmichaelia. The stipules 

 vary much in size, &c. (see Acacia, Lathyrus, Vicia). The 1. usu. 

 perform sleep-movements at night, some moving upwards, some 

 downwards, or in other ways, but finally usu. placing the leaflet edge- 

 wise to the sky. In Mimosa and Neptunia the 1. are sensitive to a 

 touch and at once assume the sleep-position, recovering after a time. 

 In Desmodium gyrans the lat. leaflets execute continuous spontaneous 

 movements as long as the temperature is high enough. 



Infl. apparently always racemose, but with variety; simple raceme 

 very common, also panicle and spike. Dorsi ventral racemes, re- 

 sembling the cymes of Boraginaceae, also occur (e.g. Dalbergia). The 

 fls. are regular (and then frequently polygamous) or irreg. (and then 

 usu. $ ) ; recept. usu. convex or flat, so that at most the fl. is slightly 

 perig. K developed in ascending order, usu. 5-merous, the odd (oldest) 

 sepal anterior ; the sepals united. C polypetalous, alt. with the K; 

 aestivation valvate(Mimosoideae), ascending imbr. (Caesalpinioideae), 



Floral diagrams of Vicia Faba (Papilionatae) and Acacia latifolia 

 (Mimosoideae), after Eichler (modified). 



