32 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. X, NO. 2. 



since the floral shoots always die off after the ripening of the seeds while the stolons and the 

 bulbs winter over. 



The structure of the seedling showed very plainly that the shoot is not monopodial but that 

 it is terminated by an inflorescence, as in the specimens that had developed from stolons, as 

 figured and described in the preceding. 



If we now compare Gray's systematic classification of the species with our table, based upon 

 the structure of the shoot alone, it is evident that certain species, otherwise closely related, have 

 become separated from each other and referred to distinct sections, in some instances to sections 

 of their own — monotypic. The members of Euclaytonia have been divided, and both C. 

 sarmentosa and ('. asarifolia appear to be distinct from these and distinct among themselves. 

 Li in nia, on the other hand, stays unchanged, and so do the monotypic Aldnastrum and JVaiocrme, 

 besides Montwsbrwm,. So, after all, the systematic classification compares fairly well with our 

 arrangement of the species, and of the two the former is, no doubt, the most natural, even if 

 some of the species may represent very distinct biological types. 



Nevertheless, several analogies exist by which these types pass over into each other, and 

 by which the genus becomes actually quite definite and naturally outlined. Not speaking of the 

 uniformity in floral structure observed in all the species, the shoot itself, with its branches and 

 root system, does also show some degree of uniformity, at least in a general way. The inflorescence 

 is of the cymose type throughout the genus; the monopodial structure is common to nearly all 

 the species, annuals as well as perennials; the primary root stays as a more or less typical taproot 

 in most of the species; finally, the tendency of developing bulblets is well expressed in some of 

 these plants. 



IV. THE ANATOMICAL STRUCTURE OF THE VEGETATIVE ORGANS. 



While dried and pressed material may be sufficient to the study of a part of the morphologi- 

 cal structure, it is seldom of much use for anatomical purpose, especially not when the plants 

 are more or less succulent, as in the present genus. We therefore regret that our material 

 preserved in alcohol only consists of a few species, collected from time to time; but whatever 

 importance may be attached to the result of our investigation, a brief sketch of the anatomical 

 peculiarities of some of these species may serve, at least, as a modest contribution to the 

 knowledge of these plants heretofore but little known from this particular point of view. 



THE ROOT. 



The somewhat modified structure of the roots in certain species necessitates the treatment of 

 these to themselves. We may begin with O. megarrhiza. In this the ultimate ramifications 

 of the lateral roots are the only ones wherein the primary arrangement of the tissues is still 

 preserved and of which the structure is identical with that of a normal root, We notice 

 here a hairy epidermis, covering a hypoderm of very wide cells, inside of which there is a 

 cortical parenchyma, consisting of only two layers, the innermost differentiated as a thin-walled 

 endodermis. The pericambium is similarly thin-walled and continuous, surrounding a central 

 linear group of very narrow scalariform vessels and two groups of leptome, the elements of 

 which are exceedingly narrow. 



If we now examine the slender, apical portion of the primary root in its second or third 

 year of growth, we notice a marked difference from the former by the absence of all the tissues 

 from epidermis to the pericambium, inclusive. The root has grown in thickness, and the peri- 

 cambium has now. by rapid cell division, developed several (about five) peripheral strata of cork 

 and a secondary cortex, which consists of about twelve layers of starch-bearing cells. The inner- 

 most portion of the central cylinder shows a number of vessels, in the center of which the primor- 

 dial are quite distinct from the younger by their narrow lumen. The leptome is located outside 

 the wider vessels, separated from these by broad strata of eambial tissue, which extends also 

 between the leptomatic groups themselves, thus covering the oldest part of the hadrome— the 

 protohadrome vessels. This structure is, to some extent, also observable in the thickest roots. 



