Barnardiella: A New Genus of the Iridaceae and Its Relationship to Gynandriris and Moraea

Abstract

The discovery of the presence of a sterile ovary tube in a plant known both as Homeria herrei and Gynandriris spiralis led to a detailed study of the characteristics of this species. A chromosome number of n = 10 suggests that the species belongs neither to Homeria or Gynandriris but may have been derived from the genus Moraea independently, though it has characteristics of Homneria and Gynandrfiris. The species is thus assigned to a new genus as Barnardiella spiralis (N.E. Br.) Goldblatt. In the course of field studies on South African Iridaceae, I was surprised to discover that the fairly common Namaqualand species known as Homeria herrei possessed a well-developed ovary tube, a fact not noted in the description of this plant (Bolus, 1931). Careful examination of living plants and subsequently of ample herbarium material showed this character in all specimens, and confirmed that this unusual feature is exactly like the sterile prolongation of the ovary which characterizes and partly defines the genus Gynandriris. A cursory review of all the species of Gynandriris revealed that the long overlooked G. spiralis (N.E. Br.) Foster described by Baker in 1892 as a Moraea, in which genus it is an illegitimate homonym, matched Homeria herrei exactly. With the combination in Gynandriris already made, H. herrei could simply have been reduced to synonymy. However, living material on hand enabled further examination and this confirmed Bolus's description of the flower as being like that in the genus Homeria, i.e., lacking clear distinction between the inner and outer tepals, and without the typical petaloid style branches and paired crests (Fig. 1 B) of both Gynandriris and Moraea, the probable ancestor of Gynandriris. The presence in this one species of the distinguishing characteristics of two genera immediately posed the problem of the true relationship of Gynandriris spiralis/Homeria herrei. The genus probably ancestral to both Homeria and Gynandriris is Moraea (Goldblatt, 1971). Homeria is believed to have evolved from Moraea by reduction of the broad petaloid style branches and long, paired style crests and by a change from distinct inner and outer tepal whorls to ? equal tepals (Fig. 1A) (Goldblatt, 1971). In contrast, Gynandriris has a flower exactly like many species of Moraea except that the ovary is extended upwards to form a sterile tube, and with the development of the ovary tube the pedicels are much reduced in length (Fig. 1 B). The question with regard to Homeria herrei is whether it is more closely re'This study was supported by Research Grant BMS 74-18905 from the U. S. National Science Foundation. 2 B. A. Krukoff Curator of African Botany, Missouri Botanical Garden, 2345 Tower Grove Avenue, St. Louis, Missouri 63110. ANN. MissouRi BOT. GARD. 63: 309-313. 1976. This content downloaded from 207.46.13.128 on Tue, 06 Sep 2016 05:19:43 UTC All use subject to http://about.jstor.org/terms 310 ANNALS OF THE MISSOURI BOTANICAL GARDEN [VOL. 63 FIGU:RE 1. Morphology and distribution of Barnardiella s'piralis.-A. Whole plant (x 293 ). -B. Androecium and gynoecium ( X 7). lated to Homeria, in fact a Homeria with an ovary tube, or a derivative of Gynandriris, having a simplified flower. The first possibility assumes independent origin of the ovary tube in Gynandriris and in a single species of Homeria, while the second presupposes the reduction of the style branches and crests independently in the ancestors of Hlomeria and in one specialized species of Gynandriris. The latter seems more likely since species of Moraea with partly to entirely reduced style branches and crests are known and these are certainly derived independently of Homeria. An answer to this question was sought by a chromosome study which seemed promising as both Homeria and Gynandriris are quite well known cytologically (Goldblatt, 1971). Gynandriris, with a basic chromosome number of x =6, has a characteristic karyotype with one or two metacentric chromosomes and a very large satellite. Homeria, also with x =6, has by contrast only submetacentric to acrocentric chromosomes and one or two usually small satellites.