ANATOMY OF CHLORIS PETKAEA. 



291 



us 



md slii(litly inii)ivssed veii- 

 mestome bundle nt tho aj)ox 

 keel. Hairs none. 



hiilliforin cells in a iaih(M' 



-5"*.. 



Fig. d8.—Chlnris])etruea— ventral portion of leaf blade. 

 Transverse section, showing epidermis (£/>) and 

 subepidermal stereome (St); at M the me.stome 

 sheath of a bundle, bordering on layers of colorless 

 parenchyma. Scale 240. 



dry, strongly keeled on tiie dorsal face 

 trally opposite the niidvein, with a large 

 of and 3 smaller ones on each side of th( 



Epidermis: Ventral, differentiated 

 wide band above the keel and 

 in 2 small groups of al)Out 4 

 cells each, 1 between the first 

 pair of nerves on each side of 

 the keel; elsewhere plurieellu- 

 lar (3 or 4 layers) and occu- 

 pying more than one-half of 

 the thickness of the leaf, ex- 

 cept above the larger nerves, 

 thin-walled (excei^t the outer 

 wall of the outermost layer) 

 and large (except the single 

 outermost la3^er where it lies 

 above the subepidermal groups of stereome) ; stomata none. Dorsal 

 epidermis one-layered, with cells all small, the outer wall and cuticle 

 much thickened, radial walls thin, undulate, one row of short cells 

 with strongly silicified walls alternating with several rows of long ones, 

 many of the cells developed into rounded, not silicified, papillae; 



stomata in the strips of epi- 

 dermis which lie between 

 the nerves, level with the 

 epidermal surface. 



Subepidermal stereome 

 (fig. 38) in flattened sup- 

 ports above and 1)elow the 

 mestome bundles, that on 

 the ventral side in 1 or 2 

 layers above the lai-ger 

 nerves, reduced to small 

 groups (sometimes only 2 

 cells) above the smaller 

 ones; on the dorsal side 

 supports stronger, some- 

 times 3-layered; also in 

 the leaf margins. 



Chlorencli y /// a , pa 1 i sade, 

 arranged radially in a sin- 

 gle row of cells on each 

 side of each mestome l)undle, with a "l)ri(lge" of small-celle<l ehlo- 

 renchyma, containing usually a few cells of colorless parenchyma, 

 connecting each 2 neighboring i-ows; chlor<)])hylI likewise in Hie 

 parenchyma sheath where it adjoins the palisade. 



Fig. 39.— CIdoris j^etraea— large mestome bundle from leaf 

 blade. St, stereome of lower face of blade, bordering on 

 the mestome sheath (M), which encircles both tlie lep- 

 tome and hadrome as a closed sheath of thick-walled, 

 porous cells. Bordering on the mestome sheath is a 

 green parenchyma sheath (P). VV, vessels; L, lacuno 

 with an annular vessel. Scale 560. 



