120 THE LOCUST TREE. 



along the margins, as if a leaf were transformed into the pis- 

 til, and (like the leaf of a Begonia when planted) produced 

 buds at its edges.* 



The Seed is so large (4) that it may be analyzed without 

 a microscope. Remove the testa and you find within, the 

 embryo- alone, as in the seed of the Apple. This consists of 



2 large cotyledons, and between them (5) a conspicuous rad- 

 icle and plumule. 



GERMINATION. Out of the thick cotyledons, the radi- 

 cle and plumule draw their first nourishment and wake into 

 life and growth. In the figure (6), the radicle has sent forth 



3 rootlets tending downward, and the plumule, a stem tipped 

 with a bud tending upward. 



The Name is the ancient Latin Pisum ; P. satlvum, 

 that of the species, indicates that the seed is sown in 

 gardens. Its native country is unknown. 



Scientific Terms. Alae. Banner. Cannae. Cirrhous leaves. 

 Diadelphous. Front suture. Keel petals. Legume. Papilionaceous. 

 Rachis. Stipels. Vexillum. Wing petals. 



* The fruit, as well as each organ of the flower, is a modified leaf, or leaves. The 

 simple fruit, formed of a single pistil, like the achenium of the Crowfoots or the 

 legume of the Pea, is a single leaf. It is folded upward so that its upper surface 

 becomes the inner, and its united edges the placentae where the seeds are developed. 

 In the Peach, another simple fruit, the upper skin of the leaf is transformed. into the 

 stone, inclosing the one seed ; the tissue into the pulp, and the lower cuticle into the 

 downy, blushing rind. The furrowed line on one side of the peach marks the union 

 of the two edges of the carpellary leaf. The apple is a 5-carpelled fruit formed of the 

 5 united pistils. In its construction the 5 carpellary leaves are combined with the 5 

 calyx leaves. The upper surface of the former becomes the parchment-lining of the 

 5 cells of the core, and the tissues of them all grow into the luscious pulp. The orange 

 is formed of twelve leaves, each transformed into a carpel, distinct in the pulp, but 

 completely blended in the rind, while in the gooseberry the venation of the several 

 leaves of which it is formed are still distinctly visible. The leaf is thus the rudiment, 

 type, or pattern, whence every organ of the plant is developed, modified in color, shape, 

 and structure to subserve, first, the special purposes in its own economy, and ulti- 

 mately, the interests of the animal creation, and even man himself, " to whom the 

 sweetness of the fruit and the beauty of the flower must have had reference in the 

 gracious intuitions of Him who created them both." 



