LEEK 



LEGUMES 



897 



will attain a much larger size; also can be conveniently 

 left in the trench with slight protection, and talten there- 

 from for winter use. Care mnst be talien not to cover 

 too early, as they decay easily, beginning at the end of 



1255. Essential organs of a Sweet Pea flower. 

 Calyx at C; tenth stamen at A; stigma at E. 



the foliage; this destroys their appearance. The har- 

 dier kinds are used for this purpose and will blanch 

 yellow down to the so-called stem, which is white to the 

 root. Leeks planted out in May are ready for use in 

 September; the sowings can be made earlier and later 

 to suit the time of maturing, and can be sown in 

 August and September in coldframes and winten d 

 over with slight protection, then transplanted tn 

 the open ground in April. The varieties b< --t 

 known to American gardeners are London Flag. 

 Large Musselburgh or Scotch Flag, Giant Caren 

 tan, and Large Rouen. j. Qtto Thilow. 



LEGUMES. The popular name given to a vast 

 and important family of plants, of which pea, 

 bean, clover, vetch, etc., are common representa- 

 tives. The onler is generally known as the pulse 

 family, or Leri iiminosiv . It contains nearly 450 

 genera, comprising over 7,000 species, and in 

 economic importance ranks second only to the grasses 

 (Graminece). The species of this family are distri- 



est trees. Numerous species are widely cultivated as 

 agricultural crops. Among these, beans and peas are 

 important food-plants, while clover, vetches, peas, meli- 

 lot, alfalfa, lucerne, cow-peas, etc., are valuable forage 

 crops, cover-crops, and green manures. Many of the 

 exotic species are ul' cciiiiiicni;!! importance. The ar- 

 boreal forms furni-h -irii.nniil timber and cabinet 

 woods. Many also fuiiii>li il\ i stuffs, rubber, balsams, 

 oils, etc., and some are cultivated for ornamental pur- 

 poses. 



In respect to the characterof the tiowers, the family is 

 divided into three subfamilies. In the large subdivision 

 to which the ornamental species of Mimosa and Acacia 

 belong, the flowers are small and regular and often 

 clustered in spherical or oblong heads. The stamens 

 are free or united into a tube and much exerted. In the 

 second subfamily the flowers are usually irregular, with 

 the upper petal folded inside of the others in the bud. 

 The coffee-tree, honey locust, and the Large genus Cassia 

 belong in this subdivision. Most of the native species of 



1257. A 4-! 



ed lee 



pod— Daubentonia. 



buted over the entire eartli. By far the greater number 

 are herbs and half-shrubby plants, but in the warmer 

 regions of the earth they attain the dimensions of for- 



Legumes, and all those cultivated as farm crops, belong to 

 the vast subfamily Papilionacew. In these the flower is of 

 the papilionaceous type, orpeatype(Fig.l2.'i4^ The upper 

 larger petal, called the banner, .s-, is extrrinr and folded 

 over the others in the bud. Tin- t\v.. hiliral oim-s, situa- 

 ted below the V>anner, are tin- wind's, ,f, iv, while the 

 lower pair, which are sometimes unite<l, form the keel, k. 

 The keel encloses the stamens and pistil, the latter being 

 often bent at right angles to the ovary, or coiled. Tlie 

 stamens are either free or they form a tubular sheath 

 surrounding the ovary. Often the upper one alone is 

 free, leaving a slit along the upper side of the sheath 

 (Pig. 12.5.5). These flowers are often dependent on in- 

 sects for pollination, a fact which is of great importance 

 in raising clover seed. 



The fruit of the LeguminossB is a pod or Legume, as 

 in the bean (Fig. 1256|. As a rule, the pods are one- 

 loculed, and have the seeds arranged in rows. In some 

 tribes they become several-celled by partitions which 

 arise between the seeds. These pods become constricted 

 at the partitions, and at maturity separnte into short 

 joints (see Fig 094, Vol. I). The val\ , s ,.1' Ihr pods are 

 generally papery or leathery, and opm at maiiirity, often 

 by a sudden snapping of the valves, whicli scatters the 

 seeds. In other tribes, however, the pods are indehiscent, 

 or do not split at maturity (Fig. 1257). 



The roots of Legumes have numerous small tubercles 

 scattered throughout the root-systems. Fig. 12.58. These 

 are caused by and infested with minute organisms, to 

 which the name bacteroids litis breii applied. The bac- 

 teroids are always present, tind j^robably multiply to 

 some extent in soils where Legumes have been grown. 

 They are very minute bodies, which are either rod-like in 

 form or branched in the form of a Y or a T. The infec- 

 tion of the plants has been observed to take place 

 through the ront-liairs. Witliin tin- platif the hacteroids 

 assume a new ami pei'iiliar form. Tin y grow out into a 

 branched and flexnuus thread. whii'Ii is enlarged and 

 nodulose at places. At the point of infection the root- 

 cells are stimulated to growth, producing the nodules 

 characteristic of Legumes. The threads permeate the 

 entire tubercle. The old threads finally disorganize, 

 and it is believed that their protein substances are 

 absorbed by the host. 



