Ant-Visited Extrafloral (Calyx and Foliar) Nectaries and Nectar Sugars of Erythrina flabelliformis Kearney in Arizona

Abstract

Extrafloral glands are noted on calyces of floral buds, before and during anthesis, and on petiolar stipels at early and later stages of leaf development. Liquid chromatographic sugar analysis of extrafloral and floral nectars shows that the extrafloral nectars (calyx and foliar) are fructose-glucose dominant while the floral nectar is sucrose dominant. Seven species of ants were noted visiting temporally separated calyx and foliar extrafloral nectaries, suggesting a possible myrmecophilous role. Mattei's early (1925) report of extrafloral nectaries, to which he attributed a myrmecophilous role, on the calyces and leaf petioles of Erythrina tomentosa R. Brown ex A. Richard (= E. abyssinica Lamarck ex A. DC.; Krukoff & Barneby, 1974) and on the calyces of E. hastifolia Bertoloni (= E. humeana Sprengel; Krukoff & Barneby, 1974) has been overlooked in the literature on the genus. Apparently until recently no other species in this large and widespread tropical genus has been noted to have extrafloral nectaries or to be myrmecophilous. Feinsinger & Swarm (1978) note ant use of extrafloral nectaries on E. poeppigiana (Walpers) 0. F. Cook and E. fusca Loureiro in Trinidad and Feinsinger et al. (this symposium) describe ant visitation of extrafloral-calyx glands on E. fusca and E. pallida Britton & Rose. Kearney (1894) made no mention of extrafloral nectaries in his description of E. flabelliformis. But in the since synonymized description of the same species from Baja California as E. purpusi, Brandegee (1903) described the calyx as bearing a large gland on the lower lip. Our study was initiated after preliminary observations during the summer of 1977 indicated that ants were visiting two types of extrafloral nectaries on Erythrina flabelliformis in southern Arizona. The purpose of this report is to describe the presence of calyx and foliar extrafloral nectaries on E. flabelliformis; to establish that the extrafloral nectaries produce sugars; to compare the relative proportions of glucose, fructose and sucrose in the extrafloral nectars and in the floral nectar; and to note the visitation of extrafloral nectaries by ants. Raven (1974, 1977, this symposium) has reviewed knowledge on the biology 'James E. Ambrose, Jr. translated several points in Mattei's 1925 paper and gave permission to study Erythrina on his land, Rafagas. Susan Kunz volunteered assistance in the field. James W. Berry and Charles W. Weber generously allowed J.C.S. use of their laboratory and equipment for the analysis of nectar sugars. Floyd G. Werner helped with preliminary identifications of ants. Roy R. Snelling, Los Angeles County Museum of Natural History, provided the final determinations of ant species utilized in the text. Charles H. Pickett, Peter Feinsinger, Herbert G. Baker, and Irene Baker provided us with copies of unpublished manuscripts. Herbert G. Baker and Jean L. Mills gave valuable criticisms of the manuscript. We thank all of the above for their contributions. 2 Office of Arid Lands Studies, University of Arizona, 845 North Park Avenue, Tucson, Arizona 85719. 3 Department of Plant Sciences, University of Arizona, Tucson, Arizona 85721. ANN. MissouRi BOT. GARD. 66: 472-481. 1979. 0026-6493/79/0472-0481/$1. 15/0 This content downloaded from 207.46.13.71 on Fri, 21 Oct 2016 04:52:55 UTC All use subject to http://about.jstor.org/terms 1979] SHERBROOKE & SCHEERENS-EXTRAFLORAL NECTARIES 473 of the genus Erythrina in introductory papers to the Erythrina symposia. It is a very distinct genus of Fabaceae consisting of 108 species of trees, shrubs, and a few herbs of wide distribution primarily in the tropics. Two species are native to the United States. Erythrina flabelliformis grows as a shrub on rocky outcrops in Arizona at the northern extent of its range (Conn, 1976); farther south in Mexico it attains tree form (Gentry, 1942). In Arizona Erythrina shrubs are dormant from fall until late spring. Kearney & Peebles (1960) note that the appear mainly in spring before the and Krukoff (1939) states that it is aphyllous or rarely with young leaves at anthesis. Leafing appears to be in response to summer rains (Conn, 1976) and plants remain in leaf for approximately six weeks (Krukoff, 1939). Narrow, tubularlike, hummingbird-pollinated flowers have evolved in New World species of Erythrina (Toledo, 1974; Raven, 1977) and E. flabelliformis is visited by hummingbirds in southern Arizona (Grant & Grant, 1968; Conn, 1976)': including the black-chinned hummingbird, Archilochus alexandri (personal observation W.C.S.).