Anatomy and systematics and of Xyridaceae, with special reference to Aratitiyopea Steyerm. and P. E. Berry.
Item
-
Title
-
Anatomy and systematics and of Xyridaceae, with special reference to Aratitiyopea Steyerm. and P. E. Berry.
-
Identifier
-
AAI3127854
-
identifier
-
3127854
-
Creator
-
Campbell, Lisa M.
-
Contributor
-
Adviser: Dennis Wm. Stevenson
-
Date
-
2004
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Biology, Anatomy | Biology, Botany | Biology, Genetics
-
Abstract
-
The monocot family Xyridaceae comprises about 385 species in five genera: Abolboda, Achlyphila, Aratitiyopea, Orectanthe, and Xyris . Xyridaceae are a morphologically diverse assemblage that occur in seasonally wet, usually exposed habitats, such as savannas and boggy meadows. Ninety-five percent of the species comprise the widespread genus Xyris; the smaller genera are known only from northern South America, particularly in the Guayana Highlands.;The family is considered related to Eriocaulaceae, and is presently included in the broadly defined order Poales. While systematists generally agree about these relationships, hypotheses that Xyridaceae are not monophyletic have not been critically evaluated. Assessments of relationship have thus far been hindered by the fact that many Xyridaceae are morphologically poorly characterized, particularly the rare, monospecific genera Achlyphila and Aratitiyopea. Presented here are structural descriptions of Aratitiyopea lopezii, a morphological survey of Xyridaceae and related taxa, analyzed using parsimony, and summarized in a generic monograph.;Although the gestalt of Aratitiyopea is aberrant in Xyridaceae, it is structurally consistent with the family, and unusual features are interpreted as adaptations to its relatively mesophytic habitat, shared by few Xyridaceae. The vegetative anatomy exhibits a combination of mesomorphic features and adaptations to seasonal drying. The family is characterized by plants with a basal rosette of leaves and a scapose spike. Plants of Aratitiyopea have relatively long, decumbent stems, with broad, cauline leaves, and a congested, showy, compound raceme. The large, tubular flowers have a uniseriate androecium of epipetalous stamens, and fleshy appendages on top of the ovary. These features, along with highly ornamented, inaperturate pollen are most similar to those exhibited by Orectanthe and Abolboda.;Parsimony analysis resolved Xyridaceae as monophyletic with two main lineages: one consisting of Xyris, and the other of Achlyphila sister to Aratitiyopea-Orectanthe and Abolboda. This represents a novel hypothesis of relationship in Xyridaceae, because Achlyphila is generally considered to be sister to Xyris, and highlights the need for a critical evaluation of the structure of Achlyphila. Synapomorphies of Aratitiyopea and Orectanthe are the presence of large flowers, a protruding anther connective, and the gynoecium appendages located on the ovary (vs. on the style).
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
