Abolboda Humb. in Humb. & Bonpl.
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Authority
Carlquist, Sherwin J. 1960. Anatomy of Guayana Xyridaceae: Abutboda, Orectanthe and Achtyplola. Mem. New York Bot. Gard. 10: 63-117.
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Family
Xyridaceae
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Scientific Name
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Description
Species Description - 1. A. acaulis. Endodermal cells in this species (fig. 3) are very thick-walled, with a small lumen which is nearer the outer than the inner surface of the endodermis. The stele is tetrarch or pentarch; no central vessel is present. The pericycle is unbroken. 2. A. acicularis (fig. 6). The endodermis is composed of cells only moderately thicknened on all surfaces. The inner wall is very slightly thicker than the radial or inner wall. Monarch, tetrarch, and 8-arch conditions were observed; in the last-named, a central vessel was present. Interruption of the pericycle by vessels is various, and both a single and all but a single vessel in contact with the endodermis were observed in different roots. 3. A. americana (fig. 5). In all the numerous roots examined, comprising several collections, the endodermis was composed of cells the inner walls of which were markedly thickened. This thickening tapers on the radial walls to rather thin at their juncture with the outer walls, on which no thickening is present. The following stelar conditions were observed: 2-, 3-, 4-, 5-, and 6-arch. All vessels are in contact with the endodermis, with the occasional exception of one or two. 4 A. lincarifolia (fig. 2). The walls of the endodermal cells are thickened in a U-shaped manner, but thickenings on the radial walls are tapered abruptly to their point of contact with the exterior walls. A ring of parenchyma cells with noticeable thickenings ensheaths the endodermis. The stele is 7- or 8-arch, with one or two central vessels. Phloem groups are small and scattered; cells of the stele other than vascular elements are thick-walled. The pericycle is not interrupted by vessels. 5. A. macrostachya var. lnacrnsiachjta (fig. 4). The root observed possessed endodermal cells much more radially elongate than those of the preceding' ones. The walls are markedly thickened, with the lumen quite eccentrically placed toward the exterior side of the cells. The stele is very large, and the root observed was 15-arcli, with 15 central vessels. Phloem groups a r e small and scattered throughout the stele. The pericyele is not interrupted by vessels. 6. A. macrostachya var. robust ior. The roots observed in this variety are similar to those of the above variety, but diver in the following respects. Two, rather than one, exodermis layers are present. The parenchyma sheath around the endodermis is two cells wide at points. The two roots observed were 13-arch with 18 central vessels and 15-arch with 16 central vessels respectively. The central vessels cannot be differentiated from the peripheral ones at all points. 7. A. sprucei (fig. 1). The cortex of roots of this species is quite distinctive in consisting of only two cell layers internal to the exodermis. The outer of these layers is composed of quite large cells, the inner of smaller cells which ensheath the endodermis. Plates of small arm-parenchyma cells interrupt this condition in places. The endodermis consists of cells thickened in a peculiar fashion, so that the lumen is turbinate as seen in transectional outline. Rarely, the endodermis is two-layered (two such instances are seen in figure 1) to the extent of one or two pairs of cells per stele. The root examined was 7-arch with a central vessel. The pericyele is not interrupted by peripheral vessels.