LEEK 



rill attain a much larger size; also can be conveniently' 

 >ft in the trench with slight protection, and taken there- 

 rom for winter use. Care must be taken not to cover 

 >o early, as they decay easily, beginning at the end of 



LEGUMES 



897 



1255. Essential organs of a Sweet Pea flower. 

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



ie foliage; this destroys their appearance. The bar- 

 er kinds are used for this purpose and will blanch 

 j llow down to the so-called stem, which is white to the 

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

 ptcmber; the sowings can be made earlier and later 



;. suit the time of maturing, and can be sown in 



, ugust and September in coldframes and wintered 

 -cr with slight protection, then transplanted to 



Ie open ground in April. The varieties best 

 unvn to American gardeners are London Flag, 

 irge Musselburgh or Scotch Flag, Giant Caren- 



rn, and Large Rouen. j. Q TTO THILOW. 



LEGUMES. The popular name given to a vast 

 id important family of plants, of which pea, 

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

 res. The order is generally known as the pulse 

 mily, or Leguminotce. It contains nearly 450 

 nera, comprising over 7,000 species, and in 

 onomic importance ranks second only to the grasses 

 rVammeo?). 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 of commercial importance. "The ar- 

 boreal forms furnish structural timber and cabinet 

 woods. Many also furnish dye-stuffs, rubber, balsams 

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

 poses. 



In respect to the character of the flowers, 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 



;ed over the entire earth. By far the greater number 

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

 ions of the earth they attain the dimensions of for- 



1257. A 4-sided leguminous pod Daubentonia. 



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

 the vast subfamily Papillonacece. In these the flower is of 

 the papilionaceous type, or pea type( Fig. 1254;. The upper 

 larger petal, called the banner, s, is exterior and folded 

 over the others in the bud. The two lateral ones, situa- 

 ted below the banner, are the wings, w, w, while the 

 lower pair, which are sometimes united, form the keel, A;. 

 The keel encloses the stamens and pistil, the latter being 

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

 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 

 (Fig. 1255). 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 Leguminosae 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 separate into short 

 joints (see Fig. 694, Vol. 1). The valves of the pods are 

 generally papery or leathery, and open at maturity, often 

 by a sudden snapping of the valves, which 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. 1258. These 

 are caused by and infested with minute organisms, to 

 which the name bacteroids has been applied. The bac- 

 teroids are always present, and probably 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 root-hairs. Within the plant the bacteroids 

 assume a new and peculiar form. They grow out into a 

 branched and flexuous thread, which 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. 



