CHAPTER XXVI 



SPERMATOPHYTES 



If one were a master of all phases of technique needed for a micro- 

 scopic study of seed plants, one would need nothing more for the groups 

 below, for material ranges from structures so delicate that they need 

 more skill and patience than the coenocy tic algae to structures so hard 

 that the method for rock sections is the best way to get mounts. 



We cannot hope to give even approximately complete directions for 

 making preparations, but must be content to give a few hints which 

 may prove helpful in collecting material and in securing mounts of the 

 more important structures. We shall consider the gymnosperms and 

 the angiosperms separately, although in many respects the technique 

 is the same for both. 



GYM NO SPERM S— CYC AD ALES 

 Cycas revoluta, the Sago Palm, can be found in almost any large 

 greenhouse which keeps decorative plants. The large conservatories of 

 city parks may keep, in addition, some species of Ceratozamia or 

 Encephalartos. Only one cycad, Zamia, occurs in the United States, 

 and it is confined to Florida. In Encephalartos and Ceratozamia the 

 development of the ovule, and even the development of the female 

 gametophyte up to the fertilization period, takes place quite naturally 

 in the greenhouse, where pollination is not likely to occur; but in other 

 genera, the female cones, or at least their ovules, nearly always abort 

 unless pollination takes place. Cycas revoluta is so abundant as a 

 decorative plant on lawns in our Gulf states that artificial pollination 

 is quite practicable. Shake pollen from a male cone into a box, carry 

 it to a female plant, put some of the pollen on a piece of paper and puff 

 it over the young female sporophylls. In the greenhouse, if cycads of 

 different species, or even different genera, but of different sexes, are 

 coning, cross-pollination is likely to be successful. Even if there should 

 be no fertilization, the pollination is likely to stimulate the ovule so 

 that it may develop to nearly full size, with good archegonia. The 

 vegetative structures are natural enough, but, with the exception of 

 leaves and small roots, are not so available, since it would kill or, at 

 least, damage the plant to take pieces of the stem. 



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