ATOLL RESEARCH BULLETIN NO. 130 A BOTANICAL DESCRIPTION OF BIG PELICAN CAY, A LITTLE KNOWN ISLAND OFF THE SOUTH COAST OF JAMAICA by C. D. Adams Issued by THE SMITHSONIAN INSTITUTION Washington, D. C., U. S. A. August 15, 1969 BIG PELICAN Scale A CAY, ST. CATHERINE, JAMAICA -4 25rnett-es 2. Strand -dune associes 3.Strand - scmb associes 4. Strand- w o o d l a d association A BOTANICAL DESCRIPTION OF BIG PELICAN CAY, A LITTLE KNOWN ISLAND OFF THE SOUTH COAST OF JAMAICA 1/ by C . D . Adams - Abstract Big Pel ican Cay is an i s l a n d of 5-1/2 ac res composed e n t i r e l y of co ra l sand and lying about t h r e e miles o f f the south coast o f Jamaica. The i s l a n d has a na tu ra l f l o r a o f 44 species of vascular p l a n t s com- p r i s i n g a vegeta t ion of seve ra l s e r a 1 u n i t s , comparable with u n i t s described f o r the Flor ida Keys, and a woodland dominated by Conocarpus e r e c t u s . Within a small a r e a t h e vegetat ion reaches a high l eve l of complexity and includes no% only common t r o p i c a l seashore p l a n t s of more o r l e s s xeromorphic type b u t , within the woodland, herbs , shrubs and t r e e s of more mesophytic cha rac te r . The vegetat ion i s unusual in t h a t not only i s t h e climax dominated by Conocarpus, which i s elsewhere a t r a n s i t i o n a l o r marginal spec ies , but it lacks any s i g n i f i c a n t mangrove community. This cay exemplif ies wi th in the West Indian phytogeographical region, t h e vegetat ion of a sand cay. Acknowledgements A l l information given i n t h i s account o the r than t h a t obtained from c i t e d references o r acknowledged he re , i s the r e s u l t of t h e au thor ' s observations during February/March 1963 and October 1967. The cooperation of D r . Walter Car ter , formerly of F . A . O . , and o f M r . Michael Campbell of Kingston, whom I accompanied on v i s i t s t o t h e i s l a n d , i s g r a t e f u l l y acknowledged. I am a l s o g r a t e f u l t o M r . Richard Wiczens, l a t e l y of the Jamaican Survey Department, who arranged f o r me t o have t h e use of an a e r i a l photograph from which Figure 1 was drawn, and t o M r . R . A . Gardiner of the Royal Geographical Society, f o r answering i n q u i r i e s about o ther maps. M r . D . 0. Vickers, Director of t h e Jamaican Meteorological Service provided information about windspeeds. Pos i t ion and general desc r ip t ion of Big Pelican Cay Big Pel ican Cay i s an i s l a n d s i t u a t e d 2.9 miles SSW of Coleman's Bay o f f t h e southernmost t i p of zhe He l l sh i r e H i l l s i n the pa r i sh of S t . Catherine, Jamaica. Owing t o i t s d is tance from t h e mainland, t h i s cay does not appear on the topographical survey maps of Jamaica (1:50,000 e d i t i o n ) , but i t s p o s i t i o n i s indica ted on the maps showing the Port land Bight Cays accompanying the papers of S t e e r s , Chapman e t a l . (1944) and Chapman (1944). Admiralty Chart No. 457 (1954) also- - 1! Senior Lecturer i n Botany, Universi ty of t h e West Indies , Mona, Kingston 7, Jamaica. shows t h e cay on a r a t h e r small s c a l e . The i s l a n d i s one of few s c a t t e r e d along the almost continuous a r c o f r e e f extending north- eastwards from Port land Point . The a rea of the cay above sea - l eve l i s 22,650 square meters (5.6 acres) and a t no poin t i s i t more than 1.6 meters (5 .4 f e e t ) above sea- level . The o ldes t p a r t i s probably a t t h e eas t e rn end and the i s l a n d seems t o be increas ing i n a westward d i r e c t i o n by depos i t ion of ca lca r - eous sand l a rge ly composed of fragments of Halimeda opuntia and s h e l l s . This sand forms an undulat ing surface t o the whole i s l a n d where the re i s vegetat ion and dhere a r e no outcrops of smashed co ra l as a t Lime Cay. Lime Cay i s one o f t h e well-known Port Royal Cays outs ide Kingston harbor, and i s almost t h e same s i z e as Pel ican Cay. While Asprey and Robbins (1953) r e f e r t o Lime Cay a s cons i s t ing of "sand containing a high proport ion of the remains of the lime-encrusting Halimeda opuntia" without q u a l i f i c a t i o n , t h i s i s only t r u e of i t s leeward aspects . S t e e r s (1940) c l e a r l y d i s t ingu i shes between sh ing le cays composed l a rge ly o f exposed coarse broken co ra l ma te r i a l of which Lime Cay i s an example, and sand cays such as Pel ican Cay where even a t t h e vulnerable windward - end, t h e i s l a n d cons i s t s uniformly of sand. The 1939 Cambridge expe- d i t i o n made a very b r i e f survey of t h i s cay and no d e t a i l e d bo tan ica l descr ip t ion was included i n t h e i r pub l i ca t ions . Climatic da ta a re lacking f o r any of these cays but it i s c e r t a i n t h a t one of t h e most important f a c t o r s determining t h e i r shape and physical evolut ion, as well as t o some e x t e n t , t h e cha rac te r of t h e i r vegeta t ion , i s the cons i s t en t e a s t e r l y breeze. Wave ac t ion and s a l t spray depend on t h i s wind which a t c e r t a i n times of t h e year , e spec ia l ly i n June and J u l y , blows a t s t r eng ths up t o Force 5 f o r seve ra l daylight hours. The windward southern and eas t e rn aspects a re p ro tec ted by a shallow lagoon seve ra l hundred meters broad outs ide which the p r inc ipa l r ee f l i e s . Wave ac t ion on these beaches i n normal weather amounts t o l i t t l e more than a gen t l e lapping, bu t s a l t spray from the r ee f i s o f t en evident . Vegetation of Pel ican Cay The four main communities described by Davis (J. H. Davis, 1942) f o r the Flor ida Keys can be recognized on Pel ican Cay and account f o r a l l t he communities which occur t h e r e . These a re 1. t h e Strand-beach associes ; 2. t he Strand-dune as soc ies ; 3. t he Strand-scrub associes and 4 . t he Strand-woodland as soc ia t ion ( the map, Figure 1, shows t h e i r d i s t r i b u t i o n ) . 1. The Strand-beach Associes The pioneer vegeta t ion occurr ing almost a l l around t h e i s l a n d i n a narrow marginal zone i s not uniform and has t h r e e more o r l e s s d i s t i n c t - f a c i e s depending on t h e o the r communities with which it happens t o be i n contac t : a) Where the beach i s backed d i r e c t l y by the strand-dune associes and woodland o r t h i c k e t i s absent , t he pioneer f l o r a forms a d i s t i n c t zone with seve ra l recognizable sub-zones. The f i r s t co lonizers , of low cover va lue , a r e Sesuvium portulacastrum and Ipomoea pes-caprae, t he former being cons tant ly present and more abundant. On t h e sha rp ly r i s i n g upper beach t h i s open sub-zone i s replaced abrupt ly by Philoxerus vermicular i s which then by l e s s abrupt and in termingl ing s t ages g ives way through sub-zones dominated by Euphorbia mesembrianthemifolia and then Canavalia maritima t o t h e more s t a b l e dune community of almost pure Sporobolus v i r g i n i c u s on t h e h igher b e t t e r drained p a r t s and Paspalum distichum with Sporobolus on the lower. This s e r i e s is well shown along t h e western h a l f of the southern shore . The most obvious i r r e g u l a r i t i e s a re t o be found towards t h e extreme western t i p of the cay where the common primary invaders may be replaced l o c a l l y by Paspalum distichum and o t h e r forward dune spec ie s , namely Euphorbia mesembrianthemifolia, Canavalia maritima and Cenchrus t r i b u l o i d e s . A l l these spec ie s , except Euphorbia mesembrianthemifolia, have t r a i l i n g branches and a re dicotyledons with f l e s h y leaves o r a re g ras ses . P l an t s of Euphorbia mesembrianthemifolia a r e usua l ly bushy and may r i s e t o 45 cm (18 i n . ) t a l l . A l l t h e o t h e r spec ies i n the t ~ i c a l exoosed . . pioneer t o forward dune s e r i e s a re of lower s t a t u r e , but Philoxerus tends t o have ascending form even i n exposed p laces . b) Where t h e beach i s backed d i r e c t l y by the s t rand-scrub cactus t h i c k e t , as along t h e northwest f ac ing shore , t h e upper beach i s eroded and f requent ly has a d i s t i n c t s t e p about two f e e t h igh . Below the s h e l f so formed only a few t r a i l i n g stems of Sesuvium occur. On t h e top of t h i s s h e l f , which i s composed of deep f i n e sand, t h e r e i s a t h i n cover of the more e r e c t bushv but s t i l l f l e s h v leaved herbaceous s p e c i e s of which Cakile l anceo la t a , Philoxerus ve rmicu la r i s , Euphorbia mesembrianthemifolia and Stachytarpheta jamaicensis a r e t h e most conspicuous. c) Around t h e e a s t e r n end of t h e i s l a n d woodland extends t o wi th in a meter of high-water and thus only a very narrow zone of herbaceous pioneer vege ta t ion e x i s t s t h e r e . This c o n s i s t s of o f t e n i s o l a t e d r a t h e r pure s t ands of Cakile l anceo la t a , Sesuvium portulacastrum, Al ternanthera h a l i m i f o l i a , Phi loxerus vermicular i s and Paspalum distichum. Owing t o the s h e l t e r provided by t h e nearby t r e e s o f Conocarpus e r e c t u s , these herbaceous p l a n t s grow t a l l e r than e l s e - where on t h e i s l a n d and some of them even tend t o scramble among t h e lower branches of t h e t r e e s . The only spec ie s which i s conspic- uous i n a l l t h r e e f a c i e s of t h e pioneer zone i s Sesuvium portulacastrum. Species of t h e Strand-beach Associes Alternanthera h a l i m i f o l i a (Lam.) S tandl . At r ip lex pentandra (Jacq.) Standl . ~ a k i l e l anceo la t a ( ~ i l l d . ) 0 . E. Schulz Canavalia maritima (Aubl .) Urb . Cenchrus t r i b u l o i d e s L . I / Frequency - 0 Explanation of abbrevia t ions : o , occas ional ; 1, l o c a l ; f , f requent ; v r , very r a r e ; f - a , f requent t o abundant; a , abundant; o- r , occasional t o r a r e ; Id , l o c a l l y dominant. Colubrina a s i a t i c a (L.) Brongn. Euphorbia mesembriantbemifolia Jacq . ( E . b u x i f o l i a Sw.) Ipomoea pes-caprae (L.) R . B r . s sp . b r a s i l i e n s i s (L.) Oos t s t r . Paspalum distichum L . (P. vaginatum Sw.) Philoxerus vermicular is (L.) Beauv. Rhizophora mangle L . (seedl ings o r sapl ings only) Sesuvium portulacastrum ( L . ) L . Sporobolus v i rg in i cus (L.) Kunth Stachytarpheta jamaicensis (L.) Vahl 1 f - a v r a 1 0-r 2. The Strand-dune Associes This vegeta t ion comprises t h e low grass land community occupying t h e ex tens ive depression-in t h e middle of t h e i s l a n d and a l s o much of t h e western h a l f . A t var ious po in t s it abuts on t o a l l t h e o t h e r com- munit ies and i s t h e only one which i s continuous a t t h e present t ime. I t s s e r a 1 s t a t u s i s b e l i e d by t h e sharp boundaries e x i s t i n g between t h e grass land and t h e t h i c k e t s o r woodlands with which it is i n con tac t . This apparent ly s t a b l e f e a t u r e may be a s soc ia t ed with a h i s t o r y of goat grazing (removed i n t h e l a t t e r p a r t of 1962) and poss ib ly f i r e . On t h e o t h e r hand a t c e r t a i n p laces i s o l a t e d o r gregarious shrubs o f Morinda royoc, Capparis f lexuosa and Caesalpinia bonduc i n young s t a g e s of growth i n d i c a t e a developmental t r e n d towards t h i c k e t . There i s a l s o probably a slow f r o n t a l encroachment upon t h e grassland by t h e l a r g e r continuous a reas of Opuntia d i l l e n i i which might proceed i n oppos i t ion t o a grazing f a c t o r but be s t a b i l i z e d by f i r e . A s the Opuntia scrub i s d i s t r i b u t e d more towards s l i g h t l y h igher ground a drainage o r s o i l s a l i n i t y f a c t o r might a l s o be involved i n determining t h e p o s i t i o n of t h e boundary with t h e grassland. The grass land v a r i e s i n cover va lue t o a considerable e x t e n t , being t h i n n e s t towards t h e southwest, where it i s pa t ch i ly dominated by Paspalum, and i s i n continuous con tac t with t h e strand-beach a s soc ie s . Cover approaches completeness along t h e boundary with t h e Conocarpus woodland i n t h e no r theas t . I t i s f a i r l y c e r t a i n t h a t t h e most dense a spec t s of t h e Sporobolus grass land would burn with a hot damaging f i r e a f t e r a long per iod of drought, but t h e ind ica t ion from t h e amount of l i v i n g and dead p lan t ma te r i a l which has accumulated is t h a t t h i s does not happen f r equen t ly . In t h e extreme northern p a r t of t h e i s l a n d t h e Sporobolus grass land reaches t h e eroded beach and a l i t t l e west of t h a t t h e r e i s a r e l a t i v e l y pure and extens ive s tand of Panicum maximum. A s a r e s u l t of human a c t i v i t y along t h e middle region of t h e northwestern shore and t h e presence of a small house, s eve ra l c u l t i v a t e d p l a n t s and weeds occur independently of t h e more na tu ra l dune g ras s l and . Species of t h e Strand-dune Associes a) Dune grass land spec ie s Caesalpinia bonduc (L.) Roxb. woody invader ~ a n a v a i i a marit ima (Aubl . ) Urb . t r a i l i n g invader Capparis f lexuosa (L.) L . woody invader Cyperus p l a n i f o l i u s L . C . Rich t ight-headed rufous va r i an t Echites umbellata Jacq. Morinda royoc L . woody invader Panicum maximum Jacq . nor th s ide only Paspalum distichwn L . southwest a rea Sporobolus v i rg in i cus (L.) Kunth Tribulus c i s t o i d e s L . Turnera u lmi fo l i a L. Bushy h i r s u t e va r i an t Frequency 0 f - a 0 0 b) Cul t iva ted p l a n t s and weeds Agave s i s a l a n a Per r ine 1 Boerhavia coccinea M i l l . a l s o i n nearby dune o Casuarina e q u i s e t i f o l i a J . R . & G . F o r s t . 1 p l a n t Cenchrus brownii Roem. & Schu l t . r Cocos nuc i f e ra L. seedl ings and 6 p l a n t s * Delonix r e g i a (Boj . ex Hook.) Raf. 1 p l a n t Nerium oleander L . 1 p l a n t Por tu laca o leracea L. a l s o i n nearby dune f * A l l e x i s t i n g specimens of - Cocos were removed i n 1963 i n prepara t ion f o r an experimental p l an t ing of s eed l ings i n the no r th -cen t r a l grass land a rea . 3. The Strand-scrub Associes This comnlunity i s t h e most patchy and d i s sec t ed vegeta t ion represented on t h e i s l a n d . I t a l s o lacks uniformity i n t h e occurrence within t h e patches of gregarious shrubby spec ies surrounded by Opuntia d i l l e n i i . A l l examples of scrub have boundaries with t h e grass land and most of t h e l a r g e r a reas a l s o have boundaries with Conocarpus woodland. The d i s p o s i t i o n of scrub i n r e l a t i o n t o woodland i s c o n s i s t e n t l y towards t h e northwest o r leeward s i d e . Undoubtedly t h e s t rand-scrub a s soc ie s i s t h e most obviously s e r a 1 and uns table vegeta t ion of Pe l ican Cay. As p l a n t s of Opuntia d i l l e n i i a r e almost everywhere contiguous i n each patch of scrub and form narrow hedges around t h e l a r g e r clumps o f shrubs, it is not poss ib l e f o r man o r grazing animals t o e n t e r . Being t o t h e leeward of woodland these a reas a r e l e a s t l i k e l y t o be a f f e c t e d by wind o r s a l t spray and except a t t h e margins would not be damaged by f i r e . The community could t h e r e - f o r e be expected t o follow through a sequence of n a t u r a l s t ages leading t o woodland. A t t h e northern end of t h e l a r g e Conocarpus woodland t h e r e i s a c l e a r i nd ica t ion of t h e replacement of Opuntia by Suriana maritima. Here a s u b s t a n t i a l l y pure s tand of Sur iana r i s i n g t o 2 .5 meters (about e i g h t f e e t ) , forms a loca l ized t h i c k e t and t h i s spec ies i s ev iden t ly competing success fu l ly with t h e cac tus i n t h a t t he re a re dead o r dying p l a n t s of t h e l a t t e r within t h e t h i c k e t . Nearby a narrow cont inuat ion of t h e cac tus f r i n g e i s separa ted by a h igher hedge of Capparis f lexuosa between it and t h e woodland. The same woody spec ie s , as well as Cordia sebes tena , occur i n clumps i n t h e l a rge scrub a rea i n t h e western p a r t of t h e i s l a n d . Here enclosed by cac tus , and again probably competing success fu l lv with it a r e Cordia sebes tena t o 3 .5 meters (about 12 f e e t ) . . Capparis f lexuosa t o 2 .5 meters (about e igh t f e e t ) and Suriana maritima t o 1 . 5 meters ( f i v e f e e t ) . A t one po in t only was it evident t h a t Conocarpus was invading t h e cac tus sc rub d i r e c t l y . I t i s noteworthy t h a t everywhere assoc ia ted with Opuntia d i l l e n i i i n t h e more open scrub a r e numerous herbaceous o r woody scramblers and v ines . These tend t o cover and poss ib ly suppress t h e cac tus . The sequence of events i n t h e succession i s t h u s : 1) Opuntia d i l l e n i i and a few shrubby spec ie s invade the dune. The l a t t e r would poss ib ly succumb t o f i r e and graz ing , the cac tus only t o f i r e and only then where d i r e c t l y i n contact with combustible ma te r i a l such as dead Suorobolus : -2) t h e cactus i s weakened o r suppressed by v ines such as Canavalia maritima, Ipomoea tuba and Echi tes umbellata which thereby c r e a t e openings - with in t h e cactus a r e a now p ro tec t ed from grazing, f i r e and wind f o r , 3) t h e establ ishment of e r e c t shrubs , Suriana maritima, Capparis f lexuosa and Cordia sebes tena . Thereaf te r t h e f i e l d l aye r i s el iminated by shade and 4) Conocarpus eventua l ly t akes over . Species of t h e Strand-scrub Associes Caesaluinia bonduc IL.1 Roxb. o r i c k l v scrambler . , Canavalia maritima (Aubl.) Urb. Capparis f lexuosa (L.) L . Cordia sebestena L . Echi tes wnbellata Jacq . Ipomoea tuba (Schlecht . ) G . Don Morinda royoc L . Opuntia d i l l e n i i (Ker-Gawl.) Haw. Suriana maritima L . Tr ibulus c i s t o i d e s L . twiner s t r a g g l i n g shrub shrub o r small t r e e twiner twiner twiner e r e c t shrub t r a i l i n g herb Frequency 0 f 0-f 1 r f - a 0 d f r 4. The Strand-woodland Associat ion The most advanced and s t a b l e community on Pel ican Cay, and t h a t which must be regarded as t h e l o c a l climax, i s t h e woodland dominated by Conocarpus e r e c t u s . This woodland occupies one q u a r t e r of the t o t a l a r e a a t t h e eas t e rn end and occurs a l s o i n two smal le r patches i n t h e south-center and southwest. The t r e e s i n t h i s woodland a re r a t h e r evenly spaced, being on an average about four meters (13 f e e t ) a p a r t , r i s e t o a general he ight of about s i x meters (20 f e e t ) with occasional t a l l e r examples and form a nea r ly c losed canopy. A few o t h e r spec ie s , numerically i n s i g n i f i c a n t i n t h e vege ta t ion , grow t o t h e same dimensions as t h e Conocarpus and inc lude Bursera simaruba, Metopium brownei and Citharexylum frut icosum. Around t h e margins of t h e woodland t h e Conocarpus t r e e s tend t o be of lower s t a t u r e except along the northern shore . This i s ev iden t ly due t o wind i n the sou the r ly and e a s t e r l y margins but may be due t o youth along the boundary with t h e dune. The t r e e s seem t o be invading t h e dune slowly and a re mixed h e r e with the shrubby Capparis f lexuosa . Within t h e woodland t h e o ld t runks of Conocarpus, greyish-brown i n co lo r and deeply long- and c r i s s - c r o s s - f i s s u r e d , a r e mainly t i l t e d and gnarled s o t h a t some of t h e l a r g e r branches reach t h e ground. Gir ths of these t r e e s range from 89 cm (35 i n . ) t o 140 cm (55 i n . ) . There i s a subs id i a ry t h i n l y d ispersed s t ra tum of shrubs and small t r e e s with Capparis f lexuosa , t h e commonest spec ie s , occas ional ly reaching t r e e s t a t u r e . Although t h e leaves o f spec ies of Capparis vary g r e a t l y i n shape, being narrowly l i n e a r on young sap l ings and ranging t o broadly oblong (C, f lexuosa) o r l anceo la t e ( C . f e r rug inea ) , t h e two spec ie s a re e a s i l y dTstinguished by t h e leaves 07 t h e former being e n t i r e l y glabrous and those of t h e l a t t e r having s t e l l a t e s c a l e s on t h e abaxia l su r face . The western boundary of t h e main a rea of woodland i s i n contact with t h e dune grass land a t t h e southern p a r t and with scrub a t t h e nor thern p a r t where a narrow s t r i p of Opuntia d i l l e n i i extends between t h e woodland and dune. The margin of t h e woodland along t h i s boundary comprises younger p l a n t s of Conocarpus mixed with Capparis f lexuosa and C. fe r ruginea . The herbaceous spec ie s Rivina hwni l i s and Turnera - u lmi fo l i a a r e a l s o p resen t . Exposed more open and b e t t e r i l luminated p a r t s of t h e woodland have a few p l a n t s of t h e climbers Ipomoea tuba and - Canavalia maritima which may be r e l i c t from t h e scrub a s soc ie s . Along t h e e a s t e r n seashore t r e e s come c lose t o t h e beach, being separa ted from it by a narrow mixed herbaceous l i t t o r a l zone (see 1, c ) . There i s no obvious i n d i c a t i o n of edaphic d i f f e rences determining t h e boundary between t h e woodland and t h e dune but the woodland i t s e l f produces a deep l e a f l i t t e r and s u p e r f i c i a l humus i n t h e i n t e r i o r where t h e r e i s very l i t t l e herbaceous vegeta t ion . I t i s noteworthy t h a t Cyperus p l a n i f o l i u s and Turnera u lmi fo l i a occur t h e r e i n forms d i s t i n c t from those which these spec ie s adout i n t h e e ra s s l and . The woodland - forms have a much more mesophytic appearance than t h e i r counterpar t s ou t s ide t h e woodland and, combined with t h e presence of Rivina hwni l i s and a well e s t ab l i shed patch of Wedelia t r i l o b a t a , i n d i c a t e t h e dependence of t hese herbs on t h e shade and lower temperatures of t h e woodland i n t e r i o r . Species o f t h e Strand-woodland Associat ion Frequency Alternanthera h a l i a i f o l i a (Lam.) S tandl . b e t t e r lit seaward margins 1 Avicennia g e n i n a n s (L.) L . seashore margins r & 1 Bursera simaruba (L.) Sarg. r Caesalpinia bonduc (L .) Roxb. marginal climber r Canavalia maritima (Aubl .) Urb. marginal climber r Capparis fe r ruginea L . o Capparis f lexuosa (L.) L . f Citharexylum frut icosum L . v r Coccothrinax jamaicensis R.W. Read ( 2 p l a n t s ) r Conocarpus e rec tus L . d Cyperus p l a n i f o l i u s L . C . Rich diffuse-headed green v a r i a n t Gossypium hirsutum L . va r . marie-galante (Watt) J . B . Hutch. (1 p l a n t ) Ipomoea tuba (Schlecht . ) G . Don marginal climber Laguncularia racemosa (L.) Gaertn. f . seashore margins Metopium brownei (Jacq.) Urb. Torrubia ob tusa t a (Jacq.) Br i t t on (1 p l a n t ) Rivina humil is L . Solanum bahamense L . Trichostigma octandrum (L .) H . Walt. i n t e r i o r climber Turnera u l m i f o l i a L. a t t enua ted g labrescent v a r i a n t Va l l e s i a a n t i l l a n a Woodson ( 1 p l an t ) Wedelia t r i l o b a t a (L.) Hitchc. Representation of Mangrove Species on Pel ican Cay While a l l t h r e e of t h e commonly occurr ing American spec ie s of mangroves have been repor ted from Pel ican Cay they have f a i l e d t o e s t a b l i s h themselves s u f f i c i e n t l y t o form a community o r t o con t r ibu te s i g n i f i c a n t l y t o any of t h e communities a l ready descr ibed . Avicennia germinans i s represented by t h r e e p l a n t s ; one o ld t r e e mentioned by S tee r s (1940), which had reached q u i t e l a rge dimensions grew a t t h e most e a s t e r l y poin t of t h e i s l a n d bu t was f e l l e d i n about 1964. Other younger p l a n t s occur with a few p l a n t s of Laguncularia along t h e southern margins of the Conocarpus woodland. S t e e r s (1940) and p a r t y i n 1939 repor ted t h a t "near t h e southern end of t h e windward s i d e a t l e a s t fou r seed l ings of Rhizophora have taken roo t on t h e r e e f near t h e cay." One seed l ing of Rhizophora mangle was seen rooted i n the shallow lagoon about two meters o f f t h e western shore i n 1963. This p l an t was not seen i n 1967 but f i v e young p lan t s have s ince become es t ab l i shed o f f t h e southern shore. Two of these a r e sap l ings about one meter t a l l . I t i s obvious t h a t many seedl ings o f t h i s spec ie s must be c a r r i e d t o t h e cay from t h e e a s t but although some o f them root on t h e r e e f o r i n t h e lagoon they seem t o be t r a n s i e n t and none has survived t h e r e t o make a s t a b l e u n i t of mangrove vegeta t ion . The c o n t r a s t between the n e g l i g i b l e con t r ibu t ion of mangroves t o t h e vegeta t ion of t h i s i s l a n d and t o t h a t of o t h e r i s l ands where man- groves form d i s t i n c t communities of t h e i r own, emphasizes one of t h e main d i f f e rences between t h i s sand cay and t h e sh ing le cay, exemplified by Lime Cay. A f f i n i t i e s of t h e F lora Common widespread t r o p i c a l l i t t o r a l spec ie s comprise t h e e a r l y se ra1 s t ages a s would be expected. Among t h e woody components of t h e more s t a b l e phases a re West Indian u l a n t s of more l imi t ed d i s t r i b u t i o n e .g . Sur iana maritima, Cordia sebes tena and Capparis fe r ruginea . I t i s among t h i s group of l i f e forms, t h e shrubs and t r e e s , t h a t the most s i g n i f i c a n t comparisons i n f l o r i s t i c composition can be made between t h e i s l a n d s and adjacent mainland formations. Pel ican Cay i s nea res t t o t h e southern He l l sh i r e H i l l s which support a vegeta t ion of t h i c k e t and woodland on l imestone. This a rea i s c a l c a r - eous and rocky o r sandy t o the s e a . Several non-maritime spec ie s a r e common t o t h e He l l sh i r e H i l l s t h i c k e t s and Pel ican Cay; a l l have bacca te o r drupaceous f r u i t s and have not been repor ted from Lime Cay. These inc lude: Bursera simaruba Citharexylum fruticosum Coccothrinax jamaicensis Metopium brownei Solanum bahamense Torrubia obtusa ta Trichostigma octandrum Va l l e s i a a n t i l l a n a For comparison Lime Cay, which i s c lose t o t h e sh ing le , pebble and non-calcareous sand s p i t known as Pa l i sadoes , has t h e fol lowing spec ie s i n common with Pal isadoes which a r e absent from Pel ican Cay: ~ a n ~ r o v e s Avicennia germinans form in^ communities ~ h i z o ~ h o r a - m a n g l e - I I 1 , Languncularia racemosa " I I Non-mangroves Acacia t o r t u o s a Ba t i s maritima Cassia emarginata Coccoloba u v i f e r a Alteramnus lucidus (Gymnanthes luc ida ) Lemaireocereus h y s t r i x P i s c i d i a p i s c i p u l a Pi thecel lobium unguis -ca t i Stigmaphyllon emarginatum Thespesia populnea These non-mangroves a r e a l l spec ie s of some importance i n Jamaican, i f not West Indian, c o a s t a l formations and it is remarkable t h a t they do not occur on Pel ican Cay. The f r u i t s a r e mostly dry and q u i t e d i f - f e r e n t from those o f t h e p l a n t s i n t h e Pel ican Cay l i s t . I t is poss ib l e t h a t f r u i t - e a t i n g b i r d s have been r e spons ib le f o r a r e l a t i v e l y g r e a t e r con t r ibu t ion t o t h e Pel ican Cay f l o r a than t o t h e p l an t co lon i sa t ion of Lime Cay. Pel ican Cay i s much f a r t h e r than Lime Cay from t h e mainland and i t i s l e s s f r equen t ly v i s i t e d by man. Thus d i f f e rences can be a t t r i b u t e d t o proximity and opportuni ty t o some ex ten t , but i t i s be l ieved t h a t t h e s e d i f f e rences a l s o r e f l e c t an ecologica l d i s t i n c t i o n r e s u l t i n g from t h e - sand and sh ing le s t r u c t u r e recognized by S t e e r s . These two cays each have 44 spec ie s of vascular p l a n t s but only 24 spec ie s i n common. Pel ican Cay has a more mesophytic aspect than Lime Cay, emphasized by t h e absence o f both xeromorphic woody legumes and ha lophyt ic mangroves. Both i s l a n d s lack epiphytes . LITERATURE CITED Asprey, G . F . & Robbins, R . G . 1953. The vegeta t ion of Jamaica. Ecol. Monogr. 23: 359-412. Chapman, V. J . 1944. The 1939 Cambridge Universi ty Expedition t o Jamaica. Part I . A s tudy of t h e bo tan ica l processes concerned i n t h e development o f the Jamaican shore - l ine . Journ. Linn. Soc. London 52: 407-447. Davis, J . H. 1942. The ecology of t h e vegeta t ion and topography of t h e sand keys of F lo r ida . Pap. Tor t . Lab. 33: 113-195 o r Carnegie I n s t . Washington Publ. 524. S t e e r s , J . A. 1940. The c o r a l cays of Jamaica. Geog. Journ. 95 (1 ) : 30-42. S t e e r s , J . A . , Chapman, V. J . , -- e t a l . 1940. Sand cays and mangroves i n Jamaica. Geog. Journ. 96 (5) : 305-328. Other r e fe rences Bengry, R . P . 1954. Lime Cay. Natural H i s t . Notes, I n s t . Jam. 65: 69-70. S t e e r s , J . A . 1940. The Cays and t h e Pal isadoes, Port Royal, Jamaica. Geog. Rev. 30 (2) : 279-296. P l a t e 1. South shore and s ou thea s t t i p . Pioneer zone on beach ~. ~~~ (Sesuvium) backed by ~ ~ o r o b o i u s and Canaval ia . Conocarpus woodland a t e a s t e r n end s epa ra t ed from g ra s s l and by t h i c k e t i n middle d i s t a n c e . Note absence of o f f sho re p l a n t s of Rhizophora (hiarch 1963). P l a t e 2 . Southeast sho re and t i p . Conocarpus woodland i n con t ac t with Sesuvium a t l e f t . Note f i v e s a p l i n g s of Rhizophora o f f s h o r e (October 1967) . I h e r e e f i s j u s t below t h e hor izon . P l a t e 3 . Boundary of Sporobolus g ra s s l and and t h i c k e t nea r t h e nor th- c e n t r a l p a r t of t h e i s l a n d . Sporobolus and Canavalia i n l e f t foreground. Hedge of 9 u n t i a s e p a r a t e s g ra s s l and from Sur iana behind. P l a t e 4 . Typical o ld t r e e of Conocarpus in woodland. Note sapl ings of Conocarpus and s o l i t a r y p lant of Opui~tia ( i n lower l e f t corner) i n otherwise open f i e l d l a y e r .