r9871 ZONA: SABALPOLLINATION r77

Principes,3l(4), 1987, pp. 177-t82 Phenology and Biology of Sabal etonia (Palmae)in SoutheasternFlorida

Scorr Zone RanchoSanta Ana Botanic Garden, 15OONorth CollegeAienue, Claremont, CA 91711

In southeasternFlorida, along the crests Materials and Methods Pleistocenedunes of the Atlantic Coastal of Field observationsand collectionswere is found a unique habitat known as Ridge, made of the insectvisitors to S. etonia in "scrubbv flatwoods" (Abrahamson et al. a relatively undisturbedrernnant of scrubby in which canbe found Sabal etonia 1984), flatwoodsin Boynton Beach, Palm Beach ex Nash (Palmae: Coryphoideae). Swingle County, . Continuous surveillance The scrubby flatwoodshabitat is essentially of four inflorescences was undertaken which sand pine, Pinus sand pine scrub in between03:20 and 15:20 on ll June (Chapm. ex Englm.) Vassey ex clausa 1986; observationsof phenologyand cen- absentor replacedby slash Sarg.,is either susesof visitors were made at 20 Englm. var. densaLir- p:nre,Pinus elliotii minute intervals. Supplemental observa- The characteristicxero- tle & Doorman. tions were made on 17 additional inflores- phyticoaks (e.g., geminataSmall, Quercus cencesfrom 10-19 June 1986. All times myrtifulia Willd.) andmany other asso- Q. are given in 24 hour notation and in East- sandpine scrub speciesare typically ciated ern Standard Time equivalents. (seeRichardson L977, Abraham- present loads of were sampled son et al. 1984, Zona and Judd 1986). A usingfuchsin glycerinejelly (Beattie 197 I ). was made to study this palm special effort collections are deposited at the Los Florida becausethe scrubby in southeastern Angeles County Museum of Natural His- there are threatened by urban flatwoods tory; syrphid flies are deposited in the development. United StatesNational Collection of Insects, The diversity o{ in the Washington, D.C. Voucher herbarium Palmae has only recently become evident specimensare depositedat Rancho Santa (Hendersoni For example,beetles 986). Ana Botanic Garden. (Henderson I9B4), flies (Schmid I97O), (Brown I97 6), andbats (Beach I 986) Phenology are now known to be pollen vectors. Wind pollination is also known in the Palmae Sabal etonia is usually a low-growing (Read 1975). Sabal etonia exhthitsmany palm, with 3-5 leaves arising from the of the typical featuresof a biotic pollination subterraneanstem. It flowers in late May "syndrome" (Faegri and van der Pijl through July. Each individual produces 1979): conspicuousfloral display,anthesis from l-5, but typically 2 3, interfoliar synchronizedwith potential inflorescences,which are denselybranched activity, sticky pollen, floral fragrance, and and bear ca. 500-800 creamy white, fra- production. This study, however, is grant hermaphroditicflowers. Rachillae are the first to document the insect visitors of exserted well beyond the dry, papery S. etonia. peduncular bracts. The flowers have 3 178 PRINCIPES lVoL. 3I minute tooth-like calyx lobes, 3 petals each Table 1. Insect uisitors lo Sabal etonia ca. 3.1 mm long, 6 stamens about as long in Palm Beach Co., Florida. Asterisk in' as the petals, and one gynoecium of 3 fused dicates the presenceo/S. etonia pollen carpels. Anther dehiscence is latrorse, by on (oLlectedspecimens. longitudinal slits. Septal nectaries are pres- Orthopiera gYnoecium; the ent al the base of the Cryllidae gynoecium and calyx lobes are heavily I sp. indet. (Trigonidiinae) invested with tannins (Zona, pers. obs.). Thysanopiera The first flowers to open are those at Heterothripidae I sp. rndet. basal portion of the inflorescence, with the Hemiptera anthesis progressing acropetally up the Miridae inflorescence. Flowers function for only one I sp. indet. dav. and all flowers in an inflorescence Lygaeidae *Lygaeus sp. have opened within 5-7 days. Additional Coleoptera be at various inflorescences on a plant may Scarabaeidae stages of maturity and anthesis. * Eup horia sepulchr alis (Fabricius) Anthesis begins when the buds first begin Elateridae *l to open at approximately 02:40. Fra- sp. indet. Lathridiidae production begins around 03:00. grance I sp. indet. The fragrance is sweet, pungent, and very Lepidoptera noticeable even though the flower buds Lycaenidae have only just begun to open. By 05:00, Eur istry mon foaonlus (Smith) Diptera nectar is visible as small droplets at the Syrphidae time the base of the gynoecium. At this * P alp ada agr orum (Fabricius) petals have not fully spread, and the sta- Ocyptamus dimidiatus (Fabricius) mens are held together around the gynoe- * Ornidia obesa (Fabricius) * aculus (Fabricius) cium by the petals in such a way that the Me romacrus * Cer iana idezsis (Shannon) anthers' obscure the Jlor undehisced dorsifixed * Copestylum mexicanum (Macquart) stigma. At 07:00, the petals are spread' Calliphoridae and the flowers are fully open. Cochliomyia macellaria (Fabricius) Anther dehiscence occurs at 07:20- Bombyliidae 12 spp. indet. 08:00. Dehiscence occurs first in those I sp. indet. anthers flowers exposed to sun; shaded dehisce somewhat laler. Laphria sp. No visible change occurs in the stigma that might indicate its receptiveness. The Formicidae 2 spp. indet. stigmatic surface is dry and white and Scoliidae remains so until pollen and,/or dust dis- * Sc olia nobilit ala (Fabricius) colors it. Pollen was first observed on stig- Colletidae *Colletes (F. mas collected at 09:50, well after anther mandibularis Smith) Anthophoridae dehiscence, despite the fact that immedi- +Xyloco p a nicans (LePeletier) carrying ately after dehiscence, insects pollen were seen foraging on the flowers. *Apis mellifera (L.) The pattern of pollen accumulation sug- Megachilidae * Megachile albitarsis (Cresson) gests that the flowers are weakly Protan- *M. xylocopoides (F. Smith) drous. * Coelioxys asterls (Crawford) By 13:00, the anther sacs are emPty' Halictidae * Agapostemon splendens (Lepeletier) and by 14:20, nectar is detectable in only * Augochloropsis metallica (Fabricius) trace amounts. Fragrance production r 9871 ZONA: SABALPOLLINATION r79

l. Insect visitors to Sabal etonia. A. Palpada agrorum, a common syrphid fly. B. Megachile albitarsis, the principal pollinator. Arrow points to a conspicuous abdominal pollen load.

ceasesbetween l8:20 and 20:00, and by sions. This phytophagous insect apparently 03:00 on the following day, the flowers feeds on the inflorescence of Sabal etonia are brownishand attract no insects. and was found to carry pollen on its body. Three species of beetles (Coleoptera) InsectVisitors were collected on the inflorescences. A nocturnal beetle (Lathridiidae) was observed Insects from the following orders were on ten occasions, but it bore no pollen. collected from the flowers of Sabal etoniai The common phytophagous Euphoria Orthoptera, Thysanoptera, Hemiptera, sepulchralis (Scarabaeidae) was observed Coleoptera, Lepidoptera, Diptera, and feeding on floral tissues on three occasions. Hymenoptera (Table l). A click beetle (Elateridae) was found only The order Orthoptera is represented by once. It actively probed the base of the only one species of nocturnal cricket (Tri- gynoecium presumably seeking nectar and gonidiinae), which was observed on the carried pollen on the ventral surface of its inflorescences on four occasions. Its noc- body. turnal visits were infrequent and seden- The , Euristrymon fauonius tary, and it carried no pollen. Thrips (Lepidoptera: Lycaenidae) was observed (Thysanoptera) were very abundant in the foraging for nectar on four occasions. Its flowers. visits were sporadic and haphazard, and Two species of Hemiptera were col- the species carried no pollen on its body. lected from the inflorescences. The first, Diptera were very common visitors. a small nocturnal species(Miridae), carried Syrphid flies (Syrphidae) were represented no pollen and was observed only three by 6 species, most frequentLy by Palpada times. The second, a diurnal Lygaeus sp. agrorutn (Fig. lA) and Copestylum mex- (Lygaeidae), was observed on two occa- icanum. Other Diptera collected from r80 PRINCIPES [VoL. 3I inflorescences include: Cochliomyia and their pollen loads were smaller' Syr- nlacellaria (Calliphoridae) and 3 uniden- phids probably contribute modestly to the tified species of Bombyliidae. Most of these pollination of S. etonia. are represented by a single collection. The pollen-gathering bees Megachile The order Hymenoptera is abundantly albitarsis, M. xylocopoides, Augochlo' represented by two species of ants (For- ropsis metallica, Xylocopa micans, Col- micidae), one (Scoliidae), and eight letes mandibularis, and Apis mellifera bees (see Table l). The ants were fre- were all observedwilh conspicuouscor- quently observed on the rachillae but never bicular or abdominal pollen loads. Aga- in the flowers. The wasp was observed only posternonsplendens and Coelioxys asteris once but carried a significant pollen load. carried lessconspicuous amounts of pollen The bees carried large loads of pollen and on their bodies. The pollen loads of C. were very abundant and active during the mandibularis, A. splendens,and A. mel- period of pollen availability. lifera were nolably homogeneousin com- position. The bees forage systematically through inflorescences,spending up to six Discussion minutes (for M. albitarsis) in one inflo- Several of the insect specieswhich vis- rescencebefore flying to another. They ited S. etoniawere found to carry no pollen are very abundant and frequent visitors loads (see Table l). Furthermore, all of especiallyin the hours immediately follow- these insects were infrequent visitors. For ing anther dehiscence. Of the bees, M. thesereasons, they are discountedas pol- albitarsiswas the mostabundant (Fig. lB)' len vectors.The thrips (Thysanoptera)are followedby M. xylocopoides, A. metal- likewise not considered to be pollinators lica, andX. micans.Megachile albitarsis becausethey remained at the base of the was the most common of all insect visitors gynoecium never contacting the anthers (excluding thrips); on I I June, one to four or stigmas. individuals oI M. albitarsus were present ThL infrequent pollen-bearing visitors, continuously on each inflorescence from Lygaeus sp.,Euphoria sepuLchralis,Sco' 08:00 to I 3:00. The behavior,abundance, lia nobilitata, Ceriana floridensis, and, frequency, and pollen loads of the bees click beetle, are probably not important (especialy the Megachilidae and Halicti- pollinators of S. etonia. They carried dae) suggestthat they are the most likely ippreciable amounts of pollen, but their pollinators,and that S. etonia is predom- numbers were few, their visits sporadic. inantly bee-pollinated. Furthermore, Lygaeus and EuPhoria Wind pollination is highly unlikely sepulchraliswere very sedentaryfeeders. becausethe pollenof S. etoniais not trans- Their contribution to the pollination of S. ported by wind. The pollen is sticky and etonia is probably not significant' cannot be dislodged from the anthers by The syrphids most frequently foraged wind nor by shaking the flowers. on nectar during two periods, the first, Information is now available for com- before the anthers had dehiscedand later, parisonsto be made of phenologyand pol- after the anthers had been cleanedof pol- lination biology of three speciesof Sabal Ien by bees. Syrphids were not abundant foundin Florida.Brown (1973, I 976) pro- when beeswere actively foraging. The syr- vides such information for S. palmetto phids carried pollen and occasionally (Walt.) Lodd. ex J. A. & J. H. Schultes, ippeared to contact the stigmaswhile for- and Kunth (1909), citing earlier work by aging. They are probablepollen vectors; Delpino,provides a very brief assessment however,their foraging behavior was more of the phenologyand pollinatorsof. S. minor erratic comparedwith the behaviorof bees, (Ja"q.; Pers. This information shedsnew r9871 ZONA: SABALPOLLINATION 181 light on the phenological and ecological the closeproximity of habitatsof S. etonia isolating mechanismsamong these species and.S. palmetto in South Florida give cre- of Sabal. denceto the hypothesis(Zona 1985) that The phenologicalobservations pre- hybridization in ancient times may have sentedhere for S. etonia differ somewhat given rise to anotherspecies, S. miamien- from those of S. palm.ettoand S. rninor. sis Zona. Both S. palmetto andS. minor arereported Sabal etoniais a characteristicspecles to be protogynous; whereas S. etonia of the sand pine scrub habitat of the Cen- appears to be protandrous. Couriously, tral Florida Ridge (Zona and Judd 1986); protogyny,as reported for S. palmetto and however,its pollination biology throughout S. minor, is not typical of bee-pollinated the entirity of its range is not known. While palms(Henderson 1986). collecting S. etonia in Polk County, I The difference in timing of stigma observedhoneybees, Apis mellifera, love- receptivityin S. etonia as comparedwith bugs, Plecia neartica Hardy (Diptera: the other two speciesappears to represent Bibionidae), and weevils (Curculionidae: an interspecificdifference. Brown (I976) Baridinae) attracted to the inflorescences reports that stigma receptivity n S. pal- in great abundance. Large populations of tnetto beginsat 05:00, but at that hour honeybeesare maintained in the area by the stigmaof S. etoniais obscurredbeneath local citrus growers, so it is likely that the the undehisceddorsifixed anthers. Insect honeybeeis a significant pollinator in cer- visitors would not likely contact the stigma tain locales. The roles of the lovebug and of S. etonia at this stage of anthesis.The the weevil are uncertairr. timing of anther dehiscenceis similar for both species,occuring at 07:30-09:10 in Summary S. palmetto (Brown I97 6) andat O7:20- In southeastern Florida, Sabal etonia 08:00 in S. etonia. flowers in May-July. Sabal etonia has The pollinatorsof S. tninor, a wasp(Pol- many characteristics of an entomophilous lsres) and Halictus bees (Kunth 1909), palm. Its flowers are protrandrous, pro- differ markedly from those of S. etonia. ducing fragrance and nectar. The most This difference is not surprising given the. common insect visitors are flies (Diptera: very different habitatsof thesepalms (mesic Syrphidae) and bees (Hymenoptera: five deciduousforests, for S. minor). The dif- families). Their behavior, their abundance ferent pollinators and habitats are formi- and frequency, and their large pollen loads dable barriers to hybridization between suggest that bees, especially Megachile thesetwo species.Of the 24 spp. of bees albitarsis, are the major pollinators. visiting S. palmetto, the primary pollina- tors are Apis mellifera, Augachlor& pura Acknowledgments (Say), Agapostemon splendens, and Dia- lictus spp.(Brown I976). Sabal pahnetto I am grateful to Roy R. Snelling, Los is isolated from S. etonia by habitat and, Angeles County Museum of Natural His. to a great extent, by bee pollinators, but tory, for identifying the wasp and bees. S. etonia has five beesin common with S. The calliphoridand syrphid flieswere kindly palmetto. They are: Agaposternonsplen- identified by N.E. Woodley and F. C. dens, Megachile albitarsis, M. xylocop- Thompson, Systematic Lab- oides, and.Xylocopa micans along with oratory, United States Department of the introduced Apis mellifera (Graenicher Agriculture. For his comments on the 1930;Brown I973,1976). The waspSco- manuscript, I thank Andrew Henderson. Lianobilitata alsovisits both palms(Brown I thank Patricia and Roger Zona for their 1973). The sharednative pollinatorsand assistance in the field. This study was t82 PRINCIPES lVoL.3l funded in part by a grant from the South- Gneexrcnrn, S. 1930. Bee-faunaand vegetation Ent. Soc' ern CaliforniaBolanisls. of the Miami region of Florida. Ann. America23:153-174. HENDERSoN,A. 1984. Observationson pollination Llrnnerune Cmnl of Chryosophila albida. Principes 2B(3): 120- 126. ABRAHAMSoN,w. C., A. F. Josr,lsott,J. N. LevNn, 1986. A reviewof palmpollination studies. eNl P. A. PERoNL 1984. Vegetationof the Bot. Rev. 52(3\:221 259. Archbold BiologicalStation, Florida: an example KuNrH, P. 1909. Handbook of Flower Pollination, of the southern Lake Wales Ridge. Florida Sci- 3 vol. fTransl. by J. R. AinsworthDavis]. Clar- entist 47(4): 209 250. endonPress, Oxford. 1729 pp' BEAcH,J. H. 1986. Pollinationbiology of spadices REer, R. W. 1975. The genus Thrinax (Palmae: and spicateinflorescences in Cyclanthaceaeand Coryphoideae).Smithsonian Contr' Bot. I9: l- Palmae.American Jour. Bot. 73(5): 6I5-616 98. (abstract). RIcHARDSoN,D. R. 1977. Vegetationofthe Atlan- BeerrIs, A. J. 1971. A techniquefor the study of tic CoastalRidge of Palm Beach County, Florida- insect-borne pollen. Pan-Pacific Entomologist Florida Scientist40(4): 28I-330. 47(I\: 82. ScHMID,R. f970. Notes on the reproductivebiol- BRov/N, K. E. 1973. Ecologicallife history and ogy of Asterogyne martiana (Palmae).II. Pol- geographical distribution of the cabbage palm, lination by syrphid flies. Principes I4(2): 39- Sabal palmetto. Ph.D. dissertation,North Car- 49. olina State University, Raleigh, North Carolina. ZoNe, S. t985. A new speciesof Sabal (Palmae) Bnown, K. E. 1976. Ecologicalstudies of the from Florida. Brittonia 37(4): 366 368. cabbagepalm, Sabalpalmetto. Principes20(l): ZoNe, S. AND W. S. Junn. 1986. Sabal etonia 3 I0. (Palmae):systematics, distribution, ecology, and FAEGRT.K. anl L. ven DER PuL. 1979. The comparisons to other Florida scrub endemics' Principles of Pollination Ecology, 3rd ed. Per- Sidall(4): 417-427. gamon Press, Oxford. 244 pp.

Warning:ROUNDUP Herbicide Can Be HarmfultoYour Palms'Health

We read with interest the July article which included a study on the use of a post- emergentherbicide ROUNDUP. This chemicalis a non-selective,very effective,potent plant killer. Extreme caution should be used when applying ROUNDUP for weed control. It should never be sprayed near valuable plants. This chemical is usually applied with a "wipe" wick applicator which is used to the tops of weeds.Always mix and dilute according to the label-a tiny amount will go a long way. As an example, a whole clump of bamboo can be destroyedif one leaf of one cane is dipped in undiluted ROUNDUP. The chemical spreadsquickly throughout the entire plant system and provides a sure, quick kill. To eliminate irritating patches of poison ivy, fill a cup with ROUNDUP diluted by half with water and using a small paintbrush, stroke one leaf of each ivy. It is also very effective on cat-tails. While ROUNDUP may not affect some woody ornamentalsor mature palms, it is far too dangerousto use without extreme caution and complete knowledgeof i1s potency. Be awareand beware. LyltN eNl KeNNuru McKeunv