D 



316 DE, H. H. W. PEAESOX ON THE MOEPHOLOGT OF 



E 



of sporopliylls, but in the specialization of barren leaf-structures * ; and it miglit also be 



ivded as in opposition to the current view that the outer envelope is a perianth f . 

 On the other hand, if a perianth homologous with that of the Angiosperms is present in 

 the Gnetales, it is not probable that in this group it will have attained the high degree 

 of specialization which is characteristic of the perianth of the former. But the 

 unqualified use of the term " perianth " implies a homology which may be correct, but 

 of which there is at present no direct proof. 



The nature of the axillary bud is uncertain (fig. 3) ; but an examinathm of the 

 whole series of sections passing through it gives the impression that it is a female 

 flower, complete or incomplete, in an early stage of development. 



The material at present available does not contain early stages of development of com- 

 plete female flowers. Very young incomplete female flowers are showm in PI. 31. figs. 4 

 and 5. Slight swellings on the axis (figs. 4 and 5, m)^ between the insertions of the 

 outer and inner envelopes, are doubtless identical with those considered by Lotsy J to 

 represent a rudimentary middle envelope. If so, these figures may be regarded as 

 confirming the statement that these envelopes arise in acropetal succession, 



which has 



been made by previous writers (Beccari, Strasburger, Karsten, and Lotsy §). They 

 therefore correspond in development to the envelopes of the complete female flower as 

 described by the same authors. The same order of succession in development is found 

 in the ovular envelopes of Ephedra || and WelwitscJiia ^. While all recent investigators 

 are in agreement on this point, Coulter and Chamberlain ** state, without discussion, 



all three genera " there are tw^o integuments which arise in basipetal 



>> 



B. The Male Flower Microspore and Pollen-Grain. {G. G^wmon.) 



A single young pseudoandrogynous spike of G. Gnemon has been available for study. 

 It has yielded certain stages in tbe development of the male flower which have not been 

 previously described for this species. Karsten f f figures three stages ranging from the 

 early condition of the envelope to the periclinal division of the primary tapetal 

 layer. Lotsy's observations on the germination of the microspore have not yet been 

 published H. 



The internodes of the spike are somewhat longer than those of G. scandens §§, but 



' much shorter than in the African species ||||. As in G. scandens^ the flowers at the 



nodes of G. Gnemon receive their vascular supply from a single series of strands arismg 



from the leaf- traces ^^, and the capsule is Avithout the large mucilage cavity which is 



so marked a feature in the African species * 



The male flower of G. Gnemon usually bears two antbers. These are always placed 

 transversely to the axis of the spike, so tbat a longitudinal median section of the latter 

 either passes between them or through one of them. Occasionally four anthers are 



* Goebel, 1905. t Lotsy, 1899, pp. 63, 64. t Lotsy, 1899, pi. 3. fig. 14. 



§ Beccari, 1897; Strasburger, 1 879 ; Karsten, 1853; Lotsy, 1899. I| Jaccard, 1894. 



t Hooker, 1863 ; Pearson, 1906. ** Coulter and Chamberlain, 1910. ft Karsten, 1893, figs. 12-14. 

 tt Lotsy, 1899, p. 82. §§ Tearson, 1912, fig. 1 a. II || Pearson, 1912, figs. Ib&c. 



Iif Pearson, 1012, fig. 2 ; Thoday, 1912. *** Pearson, I c. figs. 2, 3, & 4. 



** 



