HIGHER LAND PLANTS 



191 



Figure 11.29 Life cycle ot an angiosperm. A, mature sporophyte; 

 B, flower; C, stamen; D-F, development of pollen; G, pistil; H-L, deve- 

 lopment of embryo soc; M, growth of the pollen tube toward the embryo 

 sac; N, release of the sperms into the embryo sac; O, developing embryo 

 and endosperm; P, mature seed; Q, seedling: em., embryo; en., endo- 

 sperm; s.c, seed coat. {Used by permission, from Arthur Cronquist, 

 Introductory Botany, Harper, New York, 1961.) 



Stage before germination is possible; otherwise, es- 

 sentially as in the Conifierae. 



SPOROPHYTE 



Structure: various; include perennial trees, shrubs, 

 and herbs, plus biennial and annual herbs. 



Sporangium: included in flowers; male sporangia 

 in the anthers and female sporangia functionally rep- 

 resented within the ovule. 



Stems: range from structures similar in their 

 heavy, secondary growth to the conifers, to herbace- 

 ous types with little or no secondary growth. 



Leaves: run the gamut of structural complexity 

 more than do the leaves of any other group of plants; 

 are frequently modified or specialized appendages 

 with distinct names; most Monocotyledoneae have 

 parallel venation and most Dicotyledoneae have net 

 venation. 



Riiols : mostly as in other spermatophytes. 



Reproduction : male plants produce male spores in 

 the form of pollen grains; fertilization takes place 

 within the ovule in an ovary of a flower. 



SELECTED READINGS 



Benson, L., 1957. Plant Classification. D. C. Heath & Co., 

 Boston. 



Chamberlain, C. J., 1935. Gymnosperms : Structure and Evo- 

 lution. The University of Chicago Press, Chicago. 



Foster, A. S., and E. M. GifTord, 1959. Comparative Mor- 

 phology of Vascular Plants. Wm. Freeman Co., San 

 Francisco. 



Galston, A. W., 1961. The Ufe oj the (,reen Plant. Founda- 

 tion of Modern Biology Series. Prentice-Hall Inc., 

 Englewood CHifi's, N.J. 



Lawrence, G. H. M., 1951. Taxonomy of Vascular Plants. 

 The Macmillan Co., New York. 



Moldenke, H. N., 1949. American Wildflowers. D. Van 

 Nostrand Co., Princeton, N.J. 



Palmer, E. L., 1949. p'leldbook of .\atiiral History. .\lcGravs- 

 Hill Book Co., New York. 



Piatt, R. H., 1942. This Careen World. Dodd, Mead & Co., 

 New York. 



Ray, P. M., 1963. The Living Plant. Modern Biology Se- 

 ries. Holt, Rinehart & Winston, Inc., New York. 



Scientific American Book, 1949. Plant Life. Simon & 

 Schuster, New York. 



Weisz, P. B., and M. S. Fuller, 1962. The Science of Botany. 

 McGraw-Hill Book Co., New York. 



Note: Identification of vascular plants requires special 



knowledge and the use of various locally oriented books or 



monographs called floras. 



