1958] 



ANATOMY OF GUAYANA MUTISIEAE PART II 



167 



Returning to Guayana Gochnatinae, the genera Stomatochaeta and Chiman- 

 taea present striking comparisons with Stenopadus in leaf anatomy. Both of 

 these genera, although they vary in leaf shape, have characteristic anatomical 

 features which are correlated with the gross morphology and texture of the leaves. 



Some of the characteristics of Stomatochaeta leaves are shown diagrammati- 

 cally in S. cymbifolia, figure 12. The epidermis of this species is unsclerified. 

 A prominent hypodermis encircles the leaf, consisting of bands of thick-walled 

 sclereids at the margins, and thin-walled sclereids in a single layer near both 

 surfaces. Around the veins, thin-walled sclereids form a bundle sheath, and 

 within this, on larger veins, a sheath of fibers is also present. No bundle sheath 



Figs. 12-16. Sections of Stomatochaeta leaves. Fig. 12. S. cymbifolia, Steyermarlc $ Wur- 

 dack 508 ; diagram of transection; symbols explained in text. Fig. 13. S. condensata, Maguire 

 40603 ; portion of leaf transection, adaxial face above. Fig. 14. S. cylindrica, Maguire 32782 ; 

 transection of leaf margin, adaxial face of leaf at right. Fig. 15. Same, face view of epi- 

 dermis. Fig. 16. Same, showing upper epidermis in transection; note abortive hair. 



