The Comparative Morphology of the Cochlospermaceae. III. The Flower and Pollen

Abstract

The flowers and pollen of Anoreuxia and Cochlospermum have been studied anatomically to contribute to determining trends of specialization and relationships of the Cochlospermaceae. Perianth vascularization consists of 10 traces in some species of Cochlospermum but is reduced to 6 or 5 in other species. Androecial development is centrifugal with the vascularization consisting of 5 or more trunk bundles. The ovary has a single, 3-5 carpellate, ramified locule in all species examined. Pollen is mostly intectate to semitectate and tricolporoidate. Floral morphology of Bixa is more specialized in some ways and less specialized in others and its placement in a separate family from Amoreuxia and Cochlospermum can be justified. While the Cochlospermaceae show similarities to many parietalian families, the floral anatomy is also compatible with that found in the Malvales. Previous papers in this series (Keating, 1968, 1970), discussed the relationships of the Cochlospermaceae using the evidence from vegetative anatomy. Although floral and pollen morphology have demonstrated value in systematics, there is no complete treatment of the flower of even a single species of Cochlospermum. The genus Amoreuxia is not known to have been anatomically investigated at all. Schnarf (1931) investigated the development of the seed of C. orinocense. His comments on the nature of the septa of the gynoecium made no mention of its vascular anatomy. In illustrating the vasculature of the perianth and androecium of C. vitifolium, Wilson (1937) pointed out that more species would have to be investigated before drawing conclusions regarding the basic nature of the vasculature in this genus. The numerous stamens and reported parietal placentation have placed the family in the Bixales-Flacourtiaceae alliance (Cronquist, 1968; Takhtajan, 1969), while vegetative anatomy (Keating, 1968, 1970) indicates malvalian affinities. Erdtman (1952) briefly described the pollen of three species of Cochlospermum and noted their resemblance to pollen of Bixa. Nair (1962) briefly described the pollen of C. religiosum. Floral anatomy and pollen of Rhopalocarpus, previously assigned to the Cochlospermaceae, has been investigated by Huard (1965a, b, c). My present purpose is to examine the floral anatomy and pollen of many species of Cochlospermaceae in order to determine more accurately the relationships of the family. 1 I am grateful to the office of Research and Projects, Southern Illinois University, for its support of this work. Valuable assistance was given by the staffs of the herbaria of the Field Museum of Natural History, Harvard University, Missouri Botanical Garden, New York Botanical Garden, and the Smithsonian Institution. Also, my thanks go to collectors and curators in many nations for their generous response to my requests for specimens. 2 Department of Biological Sciences, Southern Illinois University, Edwardsville, Illinois 62025. ANN. MISSOURI BOT. GARD. 59: 282-296. 1972. This content downloaded from 157.55.39.181 on Thu, 29 Sep 2016 05:38:57 UTC All use subject to http://about.jstor.org/terms 1972] KEATING THE FLOWER AND POLLEN OF COCHLOSPERMACEAE 283 TABLE 1. Specimens examnineda. Name Collector, source' Material Amoreuxia wrightii A. Gray von Rozynski s.n. (1932), F Bud Webster & Miller 13137, PUL Bud Wooten s.n. (1919), US Bud Axtell F-03484, SIUE Pollen A. palmatifida Mocino & Sesse Niles 425, ARIZ Bud Bixa orellana L. Tate 32, NY Bud Keating 360, 414, SIUE Bud, pollen Cochlospermum fraseri Planch. Specht s.n. (1948), US Bud Perry s.n. (1949), US Bud C. gillivraei Benth. Sprecht s.n. (1948), US Bud C. gregorii F. Muell. Perry s.n. (1948), US Bud, pollen C. orinocense Steud. Kuhlmann & Jimbo 387, SP Bud, pollen Holt & Gehringer s.n. ( 1930), US Bud, pollen Piras snt. (1947), US Bud, pollen C. parkeri Planch. Klug s.n. (1933), US Bud C. planchonii Hook. f. ex Planch. Wimbush s.n. (1962), SIUE Bud Chevalier s.n. (1910), P Bud [bem s.n. (1963), SIUE Pollen C. regium (Mart & Shrank) Pilger Hoehne s.n. (1931), SP Bud Hassler s.n. (1907-8), US Bud Dahlgren s.n. (1935), F Pollen C. religiosum (L.) Alston ex Trimen Subba Rao s.n. (1963), CAL Bud Bole s.n. (1963), BLAT Bud, pollen Yongboonkird s.n. (1963), BK Bud C. tetraporum H. Hallier Pflanz 4034, US Bud C. tinctorium A. Rich Chevalier 94, P Bud Le Testu s.n. (1922), P Pollen C. vitifolium (Willd.) Spreng. Stern, Eyde & Ayensu 1694, US Bud Rowlee & Mixter s.n. (1921), US Bud Jack s.n. (1930), US Bud Schipp 49, NY Pollen C. williamsii Macbride Williams (1929), F Bud Specimens cited according to the procedure recommended by Stern and Chambers (1960). ' Southern Illinois University, Edwardsville, designated as SIUE. MATERIALS AND METHODS Flowers and buds of Amoreuxia and Cochlospermum from a geographically diverse sampling of each genus were obtained for study (Table 1). Specimens of Bixa were available for comparison. Floral anatomy was studied from microtomed serial sections and from cleared thick sections of both dried and FPA preserved material. Thick sections were cleared using the NaO'H-Chloral hydrate method of Arnott (1959) or the peroxide-lactic acid technique of Sporne (1948). Occasionally 5% sodium hypochlorite (straight household bleach) was needed to remove dark deposits from the floral receptacle. Vascular structure of the clearings was readily visible without staining and drawings were made with the aid of a 5Ox dissecting microscope. Serial microtomed sections of most species were prepared using paraffin techniques from preserved material or from dried herbarium specimens. Staining was accomplished using Safranin 0 and Fast Green FCF for the preserved material while Methyl Violet 2B and Bismarck Brown Y proved to be the best combination for the restored material. This content downloaded from 157.55.39.181 on Thu, 29 Sep 2016 05:38:57 UTC All use subject to http://about.jstor.org/terms 284 ANNALS OF THE MISSOURI BOTANICAL GARDEN [VOL. 59 Pollen was prepared by KOH-acetolysis (Faegri & Iversen, 1964) and mounted in glycerin jelly containing safranin. Sections of some samples were made at 1 I thickness with an ultramicrotome after embedding in Epon-Araldite. Measurements of polar and equatorial axes were based on at least 20 grains per sample from acetolyzed specimens. Descriptions of floral anatomy emphasize vascularization because of its demonstrated value in determining relationships (Moseley, 1967). Descriptions of vascular events in the observations section are topographical and are designed for comparisons of the anatomy of mature flowers. Such terms as diverge from the stele refer to the appearance of vascular bundles viewed in successively higher (more distal) serial sections and yield the most efficient graphic descriptions. It should be understood that developmental interpretations of these terms will pro-