. Our native ferns and how to study them; with synoptical descriptions of the North American species. Ferns. 36 Our Native Ferns. verse slit to discharge their copious sulphur-yellow spores. The veins of the sterile portion of the plant copiously anastomose. 64. Botrychium.—In the grape-ferns the sporangia are glob- ular and arranged in double rows along the narrow segments, more or less in panicles. The veins are free in all the species, yet in the smaller, fleshy ones this may not be readily perceived. 65. Spores.—The spores of ferns constitute the fruit proper. A spore consists of two disti
. Our native ferns and how to study them; with synoptical descriptions of the North American species. Ferns. 36 Our Native Ferns. verse slit to discharge their copious sulphur-yellow spores. The veins of the sterile portion of the plant copiously anastomose. 64. Botrychium.—In the grape-ferns the sporangia are glob- ular and arranged in double rows along the narrow segments, more or less in panicles. The veins are free in all the species, yet in the smaller, fleshy ones this may not be readily perceived. 65. Spores.—The spores of ferns constitute the fruit proper. A spore consists of two distinct closed sacs and the cell contents, all of which differ from each other in chemical composition. The outer layer (exospore) consists chiefly of cellulose; the inner layer (endospore) contains some albuminous matter in addi- tion, while the cell contents consist chiefly of a thin, colorless, jelly-like substance known as protoplasm, with grains of chloro- phyll (the green coloring matter of plants), starch and oil. The exospore may be smooth or roughened by points, granules, warts, or prickles. The shape varies with different species yet all are rounded, and most are oblong or at least longer than broad. All are microscopic and many are of such a shape that they do not appear uniform, owing to the various directions from which we view them. (Fig. 15-22).. Fig. 15-22. Spores, highly magnified. Cryptogramine acrostichoides, R. Br., Lygo- dium palmatitm. Swz., CysUypterU Jragilis, Bernh., Schissea pudlla, Pursh. Acrostwhym mirernn, L., Polypodium Califomicuin, Kf., Gymnogramme iriangu- larls, Kf., Not/iolama Candida, Hoolv. (Original.) 66. The number of spores produced by a single fern is in- credible. Lindley calculated that a single frond oi Scolopendrium produced about 80 sori, with an average of 4500 sporangia in each sorus, and each sporangium containing 50 spores, making a total of 18,033,000 spores. The copious green spores of Osmunda cin- namomea or the pale yellow,
Size: 2668px × 937px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorunderwoo, bookcentury1800, bookdecade1880, bookyear1881
