500 BOTANICAL SURVEY OF DISMAL SWAMP REGION. 



margins, very thick-walled (lumen almost obliterated), interrupted by 

 numerous thin-walled tannin cells. 1 



Leucothoe racemosa (L.) A. Gray. 



Hygrophile Forest formation, usually in sunny places. 



Leaf thin, not persistent, bifacial. 



Epidermis: Cells smaller than in L. axillaris and L. cateshaei, with 

 thinner, smooth cuticle and more undulate radial walls. Stomata only 

 on the dorsal surface, much smaller than in the other species of Leu- 

 cothoe, mostly lying at right angles to the veins but with some excep- 

 tions, slightly prominent, their cuticle thin and smooth, each bordered 

 by usually four epidermis cells, of which two are parallel to the guard 

 cells (subsidiary), 2 but not otherwise differentiated. Pluricellular, 

 glandular hairs along the veins on the dorsal surface. 



Palisade in two layers, the outer compact, the inner more open, 

 with shorter (lower) cells. Pneumatic tissue less open than in the 

 persistent-leaved species. 



Hypodermal colle?ichymatic tissue in about two layers above and 

 one beneath the midvein, thai above adjoining the steroomo support- 

 ers of the mestome bundles, that below separated from it by several 

 layers of colorless parenchyma (which, like the corresponding tissue 

 in 1j. axillaris, contains crystals). 



Stereome about the mestome bundles, as in the other two species, 

 but less strongly developed; none in the leaf margins. 



Differs from the evergreen species, especially in its thinner leaf, 

 with less development of cuticle, palisade, mechanical tissue, and 

 wood. 



Pieris nitida (Bartr.) Benth. & Hook.' 1 



Hygrophile Forest formation, chiefly in sunny places. 

 Leaf thick, evergreen, bifacial, shining above. 



1 Leuoothok catesbaei (Walt.) A. Gray. 



A remarkably similar plant, occurring along streams in the Allegheny Moun- 

 tains. (Material examined in cultivation at Brookland, D. C. ) 



Leaf much as in L. axillaris. 



Stomata somewhat more irregular in position. Palisade more compact, in three 

 layers (the innermost more open). Collenehymatic tissue with thinner, less ligni- 

 tied walls. Hadrome of midvein only about one-half as great in quantity. Mid- 

 vein much more deeply impressed. 



These differences, with the exception of the position of the stomata, are possibly 

 due in part to the fact that the leaves of catesbaei examined were younger than 

 those of axillaris, although the differences in age must have been but small. 



*Niedenzu (Engler's Bot. Jahrb., vol. 11, p. 185 <1S!)0) mentions the occurrence 

 of usually four subsidiary cells adjoining the guard cells of the stomata in Leuco- 

 thoe racemosa and L. recurva. 



'Compare Niedenzn in Engler's Bot. Jahrb., vol. 11, pp. 180-182 (1890). The 

 glandular hairs of P. floribunda (Pursh) Hook. f. are figured, (. S.f. S; and the 

 stomata of P.japonica (Thunb. ) Don, (. S,ff. 11, 12. 



