American Journal of Botany 84(3): 285±297. 1997. A SURVEY OF ANTHER GLANDS IN THE MIMOSOID LEGUME TRIBES PARKIEAE AND MIMOSEAE1 MELISSA LUCKOW2 AND JAMES GRIMES L. H. Bailey Hortorium, Cornell University, 462 Mann Library, Ithaca, New York 14853; and New York Botanical Garden, Bronx, New York 14058 In a broad survey of anther glands in the mimosoid legume tribes Mimoseae and Parkieae, representatives from 30 genera with anther glands were studied using scanning electron microscopy. Four kinds of anther glands could be distinguished. The Piptadenia-type gland, found in all but four of the genera surveyed, is usually spherical to ellipsoid in shape and often borne on a stipe. The cells making up the gland vary in size among species and are often sculptured. Six different kinds of sculpturing can be recognized: smooth, reticulate, striate, rugulate, scabrate, and papillate. The Gagnebina-type gland is the least specialized, consisting of a simple extension of the connective with irregularly projecting cells. The Prosopis africana- type gland is borne ventrally between the thecae, the connective extending hump-like over the apex of the anther. The Pentaclethra-type gland, found only in the genus Pentaclethra, is distinguished by a median dorsal furrow and a ventral conical structure similar to a food body or osmophore. Anatomical sections revealed two different subtypes within the Piptadenia-type gland. Some glands are composed of a homogeneous matrix of isodiametric cells, whereas others have two layers: a peripheral layer of large radially elongated cells, and a central sphere of smaller isodiametric cells and large air spaces. Some characters of anther glands have clear taxonomic signi®cance, and more detailed surveys within genera will undoubtedly provide additional taxonomic markers. Key words: anther glands; anther appendages; anther morphology; Fabaceae; Mimosoideae; Mimoseae; Parkieae. Anther glands in the Mimosoideae are extensions of (Gymnantherae) of anther glands. Although he was be- the anther connective that have a secretory function ginning to question the reliability of this character by (Chaudhry and Vijayaraghavan, 1992; Endress, 1994). 1875 when his comprehensive treatment of the Mimo- Although connective protrusions are relatively common soideae appeared, Bentham nonetheless recognized the in angiosperms (Endress and Stumpf, 1991), it is less tribe Adenantherae (``usually glanduliferous'') as distinct common that these protrusions are differentiated as se- from the tribe Eumimoseae (``usually without glands''). cretory organs. Among the lower Rosidae, Endress and This classi®cation persisted in one form or another until Stumpf (1991) reported anther glands from Crassulaceae, 1981, when Elias combined the two tribes as the Mi- Cephalotaceae, some Mimosoideae, and some Sapinda- moseae, noting that ¯oral and pollen characters indicated ceae and Rutaceae. Tucker (1996) noted anther append- they did not form natural groups. ages among some papilionoid and caesalpinioid legumes It is surprising, then, that anther glands in the Mimo- as well as in the mimosoids. They have also been re- soideae have been so little studied. Tucker (1988) in her ported from the Myrtaceae (Beardsell, Williams, and work on the ¯oral development of Neptunia pubescens Knox, 1989; Landrum and Bonilla, 1996), Violaceae noted varying expression of anther glands between dif- (Fahn, 1979) and Solanaceae (Sazima et al., 1993). ferent sexual morphs. In male ¯owers, the glands were Until recently, anther glands have ®gured prominently dactyloid and proportionately larger than in perfect ¯ow- in the taxonomy of the subfamily Mimosoideae. In 1842, ers, and in sterile ¯owers, the staminodia occasionally Bentham recognized two subtribes in the tribe Eumimo- bear only an apical gland. Tucker hypothesized that the seae based on the presence (Adenantherae) or absence glands might serve an elater-like function in addition to acting as attractants. 1 Manuscript received 27 February 1996; revision accepted 26 Sep- Anther glands are usually reported to function in pol- tember 1996. lination (Chaudhry and Vijayaraghavan, 1992; Endress, The authors thank Dr. Shirley Tucker for sharing her pickled material with us, Kew Botanical Garden (K) for both pickled and dried material, 1994), but there is scant evidence to support this asser- the New York Botanical Garden (NY) and the University of Texas at tion. Chaudhry and Vijayaraghavan (1992) studied the Austin (TX) for dried material, the Brooklyn Botanical Garden and the development of anther glands in Prosopis juli¯ora and National Tropical Botanical Garden at Kauai for fresh material for found that they are made up of secretory cells that pro- chemical analysis, Dennis Stevenson for technical supplies and assis- duce a protein/carbohydrate exudate. The cells lyse, and tance, Shirley Tucker and Peter Endress for their careful reviews of this the exudate is passed through cuticular openings to the manuscript, Ed Cope for German translation, Beryl Simpson for sharing her unpublished data on anther glands in Prosopis, and Billie Turner exterior of the gland. Chaudhry and Vijayaraghavan also for suggesting to the ®rst author a number of years ago that micro- noted that anther glands function in pollination by pro- characters in mimosoids might be interesting. We especially thank the viding a food source to attract pollinators. people who took time from their own schedules to collect material for To date there has been no broad comparative study of us: John Freudenstein and Lourdes Rico Arce at Kew, and Dave Lor- the structure of anther glands in the Mimosoideae. The ence at Kauai. This work was supported by a grant to the ®rst author from the President's Council of Cornell Women. objectives of the present study were to: (1) survey the 2 Author for correspondence. FAX: 607-255-7979, e-mail: structure of anther glands in the mimosoid tribes Parkieae [email protected]. and Mimoseae (here referred to as the basal mimosoids) 285 286 AMERICAN JOURNAL OF BOTANY [Vol. 84 using scanning electron microscopy (SEM); (2) examine TABLE 1. Distribution of anther glands in genera of the Parkieae and the internal structure and chemistry of the glands using Mimoseae. Numbers followed by an asterisk indicate that the pres- light microscopy and histochemistry; and (3) to gather ence or absence of anther glands was impossible to determine for one or more species, i.e., the discrepancy between the total number data on mimosoid taxa and a suitable Caesalpinioid out- of species and the number of species with glands is due to lack of group (Burkea), which later can be placed in a phylo- data. Double asterisks indicate that the genus is polymorphic for genetic context. anther glands, but that not all species have been examined. MATERIALS AND METHODS No. No. species Total species sam- The SEM study included samples from most genera in the Mimoseae no. with pled/ and Parkieae from which anther glands have been reported, and one Genus species glands SEM genus from the Caesalpinioideae (see Table 1, vouchers in Appendix Parkieae 1). The only genera not examined were Leucaena (currently being stud- Parkia 31 16 3 ied by C. Hughes, Oxford Forestry Institute), and the recently described Pentaclethra 3 3 1 Lemurodendron (Villiers and Guinet, 1989) from Madagascar. Callian- Mimoseae dropsis, reported by HernaÂndez and Guinet (1990) as occasionally hav- Adenanthera 12 12 2 ing an anther appendage, was also omitted as none of the specimens Alantsilodendron 8 5 1 we examined had appendages. Two or more species were examined in Anadenanthera 2 1 1 11 of the genera, in order to provide a rough assessment of variation Calliandropsis 1 1 0 within genera. Samples of ten species were studied from both material Calpocalyx 11 10* 3 in liquid and reconstituted dried material to evaluate differences caused Cyclicodiscus 1 1 1 by preservation. It was found that dried material did not differ signi®- Desmanthus 24 1 1 cantly from material in liquid in most characters. An exception was Dichrostachys 9 3 2 Elephantorrhiza 9 9 2 surface sculpturing of the cells of the anther connective and the anther Entada 27 15** 3 gland, which was somewhat smoother and less distinct in the reconsti- Fillaeopsis 1 1 1 tuted material. In general, it was possible to score herbarium material Gagnebina 5 5 2 for cell sculpturing with some degree of con®dence, in spite of minor Goldmania 5 Microlobius differences due to preservation. Indopiptadenia 1 1 1 Material preserved in FAA (formalin-acetic acid-alcohol) was put Lemurodendron 1 1 0 through an ethanol dehydration series and critical-point dried using a Leucaena 17 5 0 Tousimi critical-point dryer. Samples were then sputter-coated using a Monoschisma 5 Pseudopiptadenia BAL-TEC sputter-coater, and observed on a Hitachi 4500-S SEM. Dried Microlobius 2 2 1 Neptunia 11 7 2 material from herbarium specimens was rehydrated in a 5% solution of Newtonia 11 6** 1 aerosol, washed, and subsequently subjected to the same treatment as Parapiptadenia 6 5* 1 the specimens in liquid. Piptadenia 26 25* 2 Terminology describing anther morphology follows Endress and Piptadeniastrum 1 1 1 Stumpf (1991). Walker and Doyle's (1976) terminology to describe Plathymenia 2 2 1 sculpturing of pollen surfaces was used to describe the sculpturing on Prosopidastrum 1 1 1 the cells of the anther glands, although our usage does not correspond Prosopis 44 34** 3 exactly since there are no perforations in the cell walls of anther glands. Pseudopiptadenia 11 10* 1