CLAYTONIA GRONOV.— THEO. HOLM. 37 



of the Rocky .Mountains, for instance. Such controversies in structural respecl arc frequent- 

 very frequent, indeed — and the present knowledge of plant structures is yet much too incomplete 

 to enable us to oiler any plausible explanation. 



It seems, however, as if the species of Claytonia which we have examined exhibit certain 

 structures which may be regarded as generic; for instance, the absence of stereomatic and col- 

 lenchymatic tissues, the structure of the stomata (in contrast to those of the monotvpic Montia), 

 the four mestome bundles in the stem, the diarchic root, the lack of trichomes, of reservoirs, 

 etc. By considering the external morphological structure of the various organs, we meet also 

 here with some certain degree of uniformity throughout, even if some of the species may be 

 regarded as very distinct from a biological point of view. 



Brookland, D. C, October, 190^. 



EXPLANATION OF PLATES. 



PLATE 1. 



Fig. 1. Bulblet of Claytonia parrifnliit, magnified. 



Fig. 2. Claytonia megarrhiza, a seedling, natural size: Cot.=the cotyledons; H=the hypocotyl; R=the primary 



root. 

 Fio. :i. Same species in the second year, natural size; letters as above. 



Fig. 4. Same species, but at a later stage, natural size; the lateral roots have grown together with the primary. 

 Fk;. 5. Claytonia sarmi mosa, natural size; r=a secondary runt developed from the stolon. 

 Fig. 6. Same species; a leafy stolon, natural size; r=secondary roots. 

 Fig. 7. Claytonia Chamissonis, natural size, showing a plant developed from a bulb, and bearing three stolons, the 



one of which is terminated by a bulb. 

 Fig. s. Claytonia diffusa ; a stem-leaf, natural size. 



PLATE 2. 



Fig. 9. Stomata of the leaf of Claytonia megarrhiza,'XS60. 



Fig. 10. Claytonia Virginica, a seedling, natural size; Cot. =the cotyledon; R=the primary root. 



Fig. 11. Same species; the tuberous portion of the primary root; P=the li •.«* leaf succeeding the cotyledon (Cot.); 



/=lateral roots; magnified. 

 Fig. 12. Same species; the blade of the cotyledon, magnified. 



Fig. 13. Same species; a seedling, showing the cotyledon and a proper leaf, l l ; natural size. 

 Fig. 14. Same species in its second year, where the filiform apex of the primary root has fallen off; letters as above; 



natural size. 

 Fig. 15. Same species, showing the globular, primary root (R) with several filiform, lateral roots of a specimen about 



four years old; magnified three times. 

 "Fig. 16. Same species; the stomata of the leafx360. 



Fig. 17. Same species; transverse section of the stem; Epid.=epidermis; Hyp. =the hypodenn. X480. 

 Fig. 18. Same species; transverse section of a filiform, lateral root; Ep.=epidermis; C=cortex; End. =endodermis; 



P. =pericambium ; L. =leptome. X840. 

 Fig. 19. The diagram of the flower of Montia rivalaris; A=theaxis; C'=the posterior, C 2 =the anterior calyx-leaf; 



copied from Almquist (I.e.). 



