. Heredity and evolution in plants. Heredity; Plants. LIFE HISTORY OF A FERN II always possess some form of annulus. As the sporangia mature the spore-case itself becomes differentiated into two distinct kinds of tissue, namely, vegetative tissue on the outside, forming the wall and reproductive tissue within, from which the spores are developed. 7. Niunber of Spores.^The number of spores pro- duced by a vigorous fern is a great revelation to one who has never given such matters. careful thought. Pro-. FiG. 13.âTypes of fern sporangia. A, Loxsoma CunninghaiAl; E, Gleichenia circinata; C, Todea
. Heredity and evolution in plants. Heredity; Plants. LIFE HISTORY OF A FERN II always possess some form of annulus. As the sporangia mature the spore-case itself becomes differentiated into two distinct kinds of tissue, namely, vegetative tissue on the outside, forming the wall and reproductive tissue within, from which the spores are developed. 7. Niunber of Spores.^The number of spores pro- duced by a vigorous fern is a great revelation to one who has never given such matters. careful thought. Pro-. FiG. 13.âTypes of fern sporangia. A, Loxsoma CunninghaiAl; E, Gleichenia circinata; C, Todea barbara; D, Thyrsopteris elegans; E, Matan& peclinala; F, Lygodmm japonicum. (Redrawn from various sourd^.) ' ââ !'-:â *'â ^ fessor Bower, of Glasgow, has called attention to thjs,f act in" the following words: , -''"' "A may be made of the numerical output of spores ffom a large plant of the Shield fern, as follows: In each sporangium 48' spores may be formed; a sorus will consist of fully 100 sporangia, usually more; 20 is a moderate estimate of the sori on an average pinna; there may be fuUy 50 fertile pinnae on one well-developed leaf, and a strong plant would bear 10 fertile leives. 48 X ico X 20 X 3° X 10 = 48,000,000. The output of spores on a strong plant in the single season will thus, on a moderate estimate, approach the enormous number of fifty ; 8. Types of Sporophylls âIn many ferns the leaves serve both vegetative and reproductive functions in about ' Bower gives this number as the characteristic output for the species Aspidium Filix-mas. In other species the number may be Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gager, C. Stuart (Charles Stuart), 1872-1943. Philadelphia, P. Blakiston's Son & Co.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectplants, bookyear1920
