346 PLANT STUMIES 



22G. The plant body. — The great body of the phmt, 

 often forming a hxrge tree, is the sjioropliyte ; in faet, the 

 gametophytes are not visihk' to oi'diuary oliservation. It 

 shoukl Ije renienibei'ed that the s2"-"'"phyt'^' i'^ distinctly a 

 sexh'ss generation, and tliat it develops no sex organs. 

 This great sporoj^hyte body is elaborately organized for 

 nntritive work, with its roots, stems, and leaves. These 

 organs are very complex in structure, being nnide uj) of 

 various tissu.e systems that are organized for special kinds 

 of work. The leaves are the most variable organs, being 

 diiterentiated into three distinct kinds: (1) foliage leaves, 

 (2) scales, and (3) sporophylls. 



227. Sporophylls. — The spiiro[)hylls are leaves set apart 

 to })roduce si)orangia, and in the pine they are arranged 

 in a strobilus, as in the Horsetails and t'lub-mosses. As 

 the group is heterosporous, however, there are two kinds 

 of sporophylls and two kinds of strolhli. One kind of 

 strobilus is made up of megasporophylls bearijig mega- 

 sporangia ; the other is made up of microsporophylls bear- 

 ing microsporangia. These stroljili are often spoken of as 

 the "flowers" of the pine, Ijut if these are flowers, so are 

 the strobili of Horsetails and CJlub-mosses. 



228. Microsporophylls.— In the pines the strolhlus com- 

 posed of mit'rospor(]phylls is t'omparativcly sn-iall (Figs. 

 od.S, d, :;()!)). Each sporopli_yll is like a scale leaf, is nar- 

 rowed at the base, and upon the lower surface are borne 

 two promini'ut s^joi-angia, which of course arc microspo- 

 rangia, and contain luici-osporcs (Fig. :iO!)). 



These structures of Seed--|)huits all received names 

 before they were identified with the corri'sponding struc- 

 tures of the lower groups. The micros|iorop1iyll was called a 

 stdiiioi^ the niicr(]sp(irangia jiiilli'ii-s((rK,A\v\ the microspores 

 piiUeii-grdins, or simply jii.lh'ii. These names are still very 

 convenient to use in connection with the Spermatophvtes, 

 but it sliould be i'eme)ul)cred tlnit they a,re simply otiier 

 names for structures found in the lower groups. 



