172 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. X, NO. 6. 



disposition of the leaves as described above. The number of green leaves on the lateral shoots 

 is somewhat variable, from two to four on the basal, and only one on the uppermost of these. 

 The flowers are surrounded by a large, green spathe, which is relatively long and acuminate in 

 this species. 



The Internal Structure of the Vegetative Organs. 



the roots. 



The fleshy, secondary roots are very hairy. An exodermis of one layer of thinwalled cells 

 with prominent foldings surrounds a cortical parenchyma of large size. This parenchyma consists 

 of about twenty strata thinwalled cells with narrow intercellular spaces and tilled with starch. 

 The endodermis and the pericainbium are thinwalled and surround six broad groups of leptome 

 alternating with six short rays of hadrome; the exact position of the proto hadrome vessels could 

 not be ascertained, since the roots had been pressed and dried. A thinwalled conjunctive tissue 

 occupied the center of the root. 



THE STEM ABOVE GROUND. 



The internodes are smooth and minutely hairy from small, clavate hairs. The cuticle is 

 thick and smooth, and covers a thickwallcd epidermis; stomata are frequent and are arranged in 

 longitudinal rows, where the cortical parenchyma extends to epidermis. Inside the epidermis 

 are three layers of very thickwallcd eollenchyma, which is frequently interrupted by the cortex, 

 as mentioned above. The cortex constitutes a rather narrow zone of thinwalled cells containing 

 chlorophyll. A thinwalled endodermis surrounds the central cylinder and borders directly on a 

 closed sheath of stereome of three layers. The mestome-bundles are collateral and are arranged 

 in three concentric bands. Of these the peripheral are very numerous and they are completely 

 surrounded by stereome. The inner band consists of ten mestome-bundles with a smaller number 

 of vessels and the innermost of only three. While the stereome is usually confined to the 

 peripheral mestome-bundles in the species of Commelina, described above, we noticed in 

 the present species, C. dianthifolia, that a small group of this tissue was also developed on the 

 leptome-side of all the inner mestome-strands. The pith is thinwalled and tilled with starch. 



THE STEM-LEAVES. 



The leaf-blade is scabrous on both faces and along the margins from two-celled, short, but 

 sharply pointed hairs and one-celled, roundish, very thickwallcd warts. Besides these some 

 clavate hairs were also observed, but only on the ventral face of the blade, and not in any large 

 number. The cuticle is thick and smooth. Viewed en face the cells of epidermis are mostly 

 octagonal; in transverse sections the cells show a wide lumen and the outer walls are moderately 

 thickened. Stomata are distributed over both faces of the blade; they are level with epidermis 

 and have two pairs of subsidiary cells parallel with the stoma. Thickwallcd eollenchyma was 

 observed on the leptome-side of the larger veins, and in the margins. The stereome is weakly 

 developed as a few strata on the leptome- and hadrome-side of the larger mestome-bundles, 

 separated from the eollenchyma by a few layers of chlorenchyma. The chlorenchyma consists 

 of one single layer of palisades, vertical on the ventral face, and of a more open pneumatic tissue 

 near the dorsal portion of the blade. Many cells were observed to contain tannin. The structure 

 of the leptome and hadrome showed nothing "I' particular interest. 



THE SPATHE. 



The structure of the spathe is almost identical with that of the leaf-blade in regard to 

 epidermis with the stomata and hairs; the wartlike papilhe were, however, not observed. The 

 mechanical tissue is somewhat poorer developed, there being only a small group of eollenchyma 

 on the leptome-side of the midvein, and stereome is totally absent. But in regard to the. chloren- 

 chyma and the minor structure of the mestome-strands we did not notice any important difference 

 between the spathe and the stem-leaf. 



