NORTH AND CENTRAL AMERICAN COMMELINACE.E— HOLM. 173 



Aneilema nudiflorum R. Br. 



The Ramification of the Shoot. 



The species is ;in annual with decumbent stems rooting at the lower nodes. The narrow 

 leaves are alternate with distinct sheaths which inclose the axillary buds; the fore-leaf is mem- 

 branaceous, tubular with the apex extended into two small, green teeth. Nearly all the shoots 

 are terminated by an inflorescence borne on a long, slender scape. In regard to the arrangement 

 of the leaves, the diagram is the same as that figured on our Plate II <>f Tradescantia rosea, i. e., 

 a regular alternation of the green stem-leaves and the fore-leaf. 



The Internal Structure of the Vegetative Organs. 



the roots. 



Two to three slender and sparingly branched roots are developed on the lower face of the 

 nodes. Their structure is as follows: Epidermis is hairy, and covers an exodermis of one layer 

 of thinwalled, pentagonal cells, which are larger than those of epidermis and the adjoining cortex; 

 no foldings of the cell-walls were observed. The cortical parenchyma consists of ten strata, of 

 which the four peripheral are persisting, while the others were collapsed- tangentially; no starch 

 was observed. The endodermis and the continuous pericambium are thinwalled. There are five 

 short hadromatic rays with one very wide, reticulated vessel in the center, and two to three 

 narrower, spiral in each ray. The leptome is well developed, and the conjunctive tissue, which 

 occupies only a small portion of the central cylinder, is thinwalled. 



the stem. 



The structure of the stem could not he studied satisfactorily, since the material had been 

 pressed and dried. We noticed, however, that a continuous sheath of hypodermal collenchyma 

 surrounded a narrow zone of green cortical parenchyma, and that the peripheral mestome-bundles, 

 located inside the cortex, had a support of stereomatic tissue on the leptome side. 



the stem-leaves. 



Viewed en face epidermis of the dorsal face consists of rectangular cells with some few rows 

 of clavate hairs between the stomatiferous strata. The stomata have one pair of subsidiary cells 

 and are slightly raised above the adjoining epidermis. The outer cell-wall of epidermis exhibits 

 a number of longitudinal ridges, which are covered by the thin but distinct cuticle. 



The ventral epidermis shows the same structure, but has no stomata. Along the margins of 

 the blade are minute, one-celled warts, but no hairs or prickle-like projections. Viewed in 

 ti'ansverse sections the leaf shows a large-celled epidermis on both faces, and the stomata have 

 deep and wide air-chambers. Underneath the ventral epidermis is a water-storage tissue of two 

 layers of very large .thinwalled cells, which covers the chlorenchyma. This tissue represents a 

 homogeneous, open pneumatic tissue, since no distinct palisades were noticed. The mestome- 

 bundles are very thin, and only the mediane has a support of hypodermal collenchyma on the 

 leptome-side; some of the other veins, had a small group of stereome on the leptome- but none 

 on the hadrome-side, and some few layers of this tissue were, furthermore, observed in the leaf- 

 margins. 



Tinantia anomala (Torr.) Clarke. 



This plant was originally described by Torrey" as a Tradescantia "anomala" and his 

 material came from the shady woods on the Blanco, Comale, and other rivers in Texas. As 

 stated by Torrey, "the species is intermediate between Tradescantia and Commelina, resembling 



«U. S. and Mex. Bound. Survey under Lieut. Emory. Washington, 1858, p. 225. 



