200 T. Holm — North American Terrestrial Orchidece. 



narrow. Endodermis is moderately thickened all around, while 

 the pericambinm is thin-walled and continuous in L. cordata. 

 Five narrow rajs of hadrome meet in the center with five rela- 

 tively wide vessels, and alternate with roundish groups of lep- 

 tome ; the conjunctive tissue is thin-walled and is only to be 

 observed between the vessels, but not in the center of the cyl- 

 inder. Hyphge were observed in epidermis, hypoderm and 

 cortex of L. cordata, but not in L. australis. 



Pogonia ophioglossoides Nutt., P. verticillata Nutt. and P. 

 divaricata R. Br.* 



Epidermis is thin-walled and densely covered with hairs in 

 P. ophioglossoides and divaricata, but less so in the third 

 species. The hypoderm is thin-walled in P. ophioglossoides, 

 slightly thickened in the others. The cortex is composed of 

 6 to 9 layers of thin-walled cells ; it is quite open in P. ophio- 

 glossoides, but very compact in the other species. Starch was 

 only found in P. divaricata. Endodermis is thin-walled 

 throughout in P. ophioglossoides and P. divaricata, but in 

 P. verticillata there is one thick-walled cell outside each group 

 of leptome. The thin-walled pericambium is continuous in 

 P. ophioglossoides, but is irregularly interrupted by the proto- 

 hadrome vessels in the two other species. The leptome repre- 

 sents quite large and roundish groups alternating with narrow 

 rays of hadrome ; 5 rays were observed in P. ophioglossoides, 

 6 in P. divaricata and 8 in the third species ; the hadrome 

 extends to the center of the cylinder in P. ophioglossoides, but 

 not in the other species. Hyphse were found in the hypoderm 

 and cortex of all three species. 



Galopogon pulchellus R. Br., C. multiflorus Lindl. and C. parvi- 



florus Lindl. 

 The root-structure is very uniform in these species and 

 resembles that of Pogonia, especially P. ophioglossoides. Epi- 

 dermis and hypoderm are thin-walled in all three species, and 

 the cortex, which, also, is thin-walled, consists of about 8 layers 

 with narrow intercellular spaces ; no starch was observed in the 

 cortex. The endodermis is thin- walled throughout, with the 

 spots plainly visible. In the central-cylinder we find a thin- 

 walled pericambium in the two first species, but one moderately 

 thickened in G. parviflorus ; it is continuous in G. pulchellus, 

 but we were unable to trace the exact location of the proto- 

 hadrome vessels in the other species, whether these had broken 

 through the pericambium or not. Five, and quite broad, hadro- 

 matic rays were observed in C. pulchellus and G. parviflorus^ 

 but only three in G. multiflorus / the innermost vessels are 

 relatively wide and border on a small, but very distinct, cen- 



* Compare this Journal, vol. ix, 1900, p. 13. 



