1 2 Outlines of Horticultural Chemistry : — 



The petals of the flower evidently act an important part in 

 nourishing the more essential parts of fructification, since, if 

 they are removed from plants naturally possessing them, I am 

 not aware of a single instance in which the seeds will advance 

 a grade further towards maturity. The stamens and pistils 

 are the most essential parts. The first are the members that 

 secrete the pollen, or fecundating dust, without the application 

 of which to the pistils the seed is never fertile. It is the 

 a7ither, or summit of each stamen, that secretes this fecun- 

 dating matter. The pollen appears to the unassisted vision 

 merely a fine powder ; but, in fact, each grain is commonly a 

 membranous bag, varying in form in different species. Pollen 

 is chiefly discharged from the anthers during dry warm 

 weather ; but each vesicle of it remains entire until it comes 

 in contact with moisture, when it immediately bursts, and 

 discharges its minute particles in a form absorbable by the 

 small ducts of the pistil. The necessary degree of moisture 

 usually exists upon the summit of the pistils, to which the 

 bags of pollen cling, and thus more securely determine the 

 impregnation of the seeds. We are furnished, by a know- 

 ledge of these facts, with a reason for the great injury occa- 

 sioned to orchards, &c., by excessive wet weather during the 

 time of flowering. The pollen is washed away from the 

 anthers as it is secreted, and, exploding at the instant, either 

 does not settle at all upon the pistils, or alights upon them whilst 

 loaded with unnatural moisture which is again shaken oftj or 

 is prevented entering their orifice. They warn us, also, from 

 watering or disturbing unnecessarily the herbage of plants 

 under our care whilst they are in bloom. It is a fact of some 

 importance to be known by the cultivators of hybrids and new 

 varieties, that in dry weather pollen may be conveyed to a 

 considerable distance uninjured. This is demonstrated by 

 many observations on accidental impregnations by the agency 

 of winds, &c. ; and still more decidedly by Linnaeus, who 

 kept some of the pollen of the Jatropha urens in paper for 

 more than a month, which afterwards fertilised the pistils to 

 which it was applied. In the present general diffusion of 

 botanical knowledge, it seems almost trite to observe that the 

 seed-grower should neither exterminate the barren plants of 

 the dioecious class, as in spinach, asparagus, &c., nor remove 

 the unfertile flowers of cucumbers, &c. ; for, without these, the 

 female blossoms would be equally unproductive. Many in- 

 sects are highly injurious in the hot-house, &c., to the plants 

 they contain ; but an indiscriminate destruction is not to be 

 recommended. Many of them bear pollen on their wings, &c., 

 to female flowers, which otherwise would remain unimpreg- 



