. Outlines of botany for the high school laboratory and classroom (based on Gray's Lessons in botany) Prepared at the request of the Botanical Dept. of Harvard University. Botany; Botany. /- « h 143. a, a stamen ; p, pollpn snr: c, connective; /", tilameiu ; h, a stamen with the anther cut through at the time of maturity". 203. The pollen-bearing organ is the stamen (Fig. 143) Its parts are the stalk, called the filament, and the anther, containing the pollen in 2) oil en sacs. In the j-oiing condition of the stamen four longitudi- nal pollen sacs are found. The whole mass of tissire
. Outlines of botany for the high school laboratory and classroom (based on Gray's Lessons in botany) Prepared at the request of the Botanical Dept. of Harvard University. Botany; Botany. /- « h 143. a, a stamen ; p, pollpn snr: c, connective; /", tilameiu ; h, a stamen with the anther cut through at the time of maturity". 203. The pollen-bearing organ is the stamen (Fig. 143) Its parts are the stalk, called the filament, and the anther, containing the pollen in 2) oil en sacs. In the j-oiing condition of the stamen four longitudi- nal pollen sacs are found. The whole mass of tissire tilling these sacs is finally con- verted to pollen. At matu- rity, if not before, the wall between the two cavities on the same side of the anther commonly disapj^ears, leaving a single pollen sac in either half-anther. The middle pai-t or axis of the anther between the two pouches thus formed is the connective. 204. The pollen sacs open for the liberation of the pollen usually by a slit along the groove running down each side of the anther; in Pyrola and other members of the Heath family, by terminal pores (Fig. 144); and in the Barberr}^ by uplifting- valves (Fig. 145). And other modes of dehiscence occur, suited to the various means by wdiich the pollen is to reach its destination. 205. The number of stamens is often large, as in the wild Rose, the Ijuttercup, the ^Magnolia, and the Water Lil)-. In a few species there is but one. Generally speaking, the number is small, not more than ten; and, when small, usually definite for each species. For example, most grasses have three sta- mens, most [Mints four, the Violets five, and the true Lilies commonly six. Each jDollen sac produces a vast number of pollen grains. And when the flowers borne. 14i, 145. Stamens: 144, of Pyrola, the autlicr opening by terminal pores; ;), of Bar- berry, the anilier opening by uplifting Please note that these images are extracted from scanned page images that may have been digit
Size: 1429px × 1749px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1901
