B L I 



90 



BLO 



BLITUM. Five species. Hardy 

 annuals. Seeds. Common soil. 



BLOOD. See Animal Matters. 



BLOOM or BLOSSOM, is the popu- 

 lar name for the flowers of fruit-bearing 

 plants. 



" The organs of fructification are ab- 

 solutely necessary, and are always pro- 

 ducible by garden plants properly culti- 

 vated. They may be deficient in leaves, 

 or stems, or roots, because other or- 

 gans may supply their places; but 

 plants are never incapable of bearing 

 flowers and seeds, for without these 

 they can never fully attain the object 

 of their creation, the increase of their 

 species. 



" Every flower is composed of one 

 or more of the following parts, viz. : 

 the calyx, which is usually green and 

 enveloping the flower whilst in the 

 bud ; the corolla, or petals, leaves so 

 beautifully coloured, and so delicate in 

 most flowers ; the stamens or male 

 portion of the flower, secreting the pol- 

 len or impregnating powder; the pistils 

 or female portion, impregnatable by 

 the pollen, and rendering fertile the 

 seeds; and lastly, the pericarp or seed- 

 vessel. 



" The stamens are the only portion 

 of a flower which can be removed with- 

 out preventing the formation of fertile 

 seed, and their loss must be supplied 

 by the induction to the pistils of pollen 

 from some kindred flower. 



" The calyx is not useless so soon 

 as it ceases to envelope and protect the 

 flower, for the nower stalk continues 

 increasing in size until the seed is per- 

 fected, but ceases to do so in those 

 plants whose calyces remain long green 

 if these be removed ; on the other 

 hand, in the poppy and other flowers, 

 from which the calyx falls early, the 

 flower stalk does not subsequently en- 

 large. 



" The corolla or petals, with all their 

 varied tints and perfumes, have more 

 important oflices to perform than thus 

 to delight the senses of mankind. Those 

 bright colours and their perfumed honey 

 serve to attract insects, which are the 

 chief and often essential assistants of 

 impregnation ; and those petals, as ob- 

 served by LinuEus, serve as wings, 

 giving a motion assisting to eff"ect the 

 same important process. But they have 

 a still more essential oflice, for although 

 they are absent from some plants, yet 



if removed from those possessing them 

 before impregnation is completed, the 

 fertilization never takes place. They 

 therefore perform in such cases an 

 essential part in the vegetable econo- 

 my ; and that they do so is testified by 

 all the phenomena they exhibit. They 

 turn to the sun open only when he has 

 a certain degree of power, and close 

 at the setting of that luminary ; their 

 secretions are usually more odorous, 

 more saccharine, and totally differing 

 from those of the other organs of plants ; 

 and in the absence of light those secre- 

 tions are not formed. 



"The corolla is not always short- 

 lived, for although in some, as the 

 cistus, the petals which open with the 

 rising sun^ strew the border as it de- 

 parts, so some, far from being epheme- 

 ral, continue until the fruit is perfected. 

 The duration of the petals, however, 

 is intimately connected with the im- 

 pregnation of the seed, for in most 

 flowers they fade soon after this is com- 

 pleted ; and double flowers, in which 

 it occurs not at all, are always longer 

 enduring than single flowers of the 

 same species. Then, again, in some 

 flowers, they become green and per- 

 form the function of leaves after im- 

 pregnation has been effected. A fiimi- 

 liar example occurs in the Christmas 

 rose, (Helleborus niger,) the petals of 

 which are white, but which become 

 green so soon as the seeds have some- 

 what increased in size, and the stamens 

 and other organs connected with fer- 

 tility have fallen off. 



" It is quite true that some fruit will 

 not ripen if the part of the branch be- 

 yond is denuiied of leaves, but this 

 only shows that those fruits cannot ad- 

 vance when deprived of leaves as well 

 as of calyx and corolla, the only organs 

 for elaborating the sap ; and there are 

 some flowers, as the Daphne mezereon, 

 Autumn crocus, and sloe, that have 

 their flowers perfected and passed 

 away before the leaves have even ap- 

 peared. 



" That the petals perform an im- 

 portant part in elaborating the sap sup- 

 plied to the fruit is further proved by 

 the flower being unable to bloom or to 

 be fertile in an atmosphere deprived of 

 its oxygen; and by their absorbing more 

 of that gas, and evolving more car- 

 bonic acid, than even a larger surface 

 of leaves of the same plant. 



