29 PRINCIPES lVoL. 64 Principes,2g(2), I985, PP. 64-71 Pollination of Socrateaexorrhiza and Iriartea ventncosa ANonrw HnNlrnsoN New York' NY IO45B The New York Botanical Gard'en, Bronx' and pollination of the genera' although ABSTRACT B"lloik (l98l) reported that in Costa Rica and Inflorescence morphology, development' u"lyt":: Socratea d,urissima was Protogynous (Mart') H' A' Werdl' ui.itorc of Socratea'exoriiiza beetle pollinated, and Iriartea giganLeo uentricosaMart' were observed in u-nd Iriorr"o *., protund.ous and bee pollinated' The .orth"r. Venezuela. Beetle and bee pollination' of the present study was to hves- respectivelY,were found' The taxonomic significance o,rroor" pollen in relation to "f itr" r"."t,. is discussed. Floral anatomy, iig"i" poUittution syndromes are morphology, and the role of peduncular bracts taxonomy. considered. Materialsand Methods ResuurN The studysite was the Cerrode Ia Ne- e insectos v;sitantes La morfologia, el desarrollo' blina Expedition's base camp, situated exorrhiza (Matt') -at d" la, itflo.e.Jetcias de Socratea Grande on the Mart' fueron the mouih of the Caffon i. .t. W"tat. y lriartea aentricosa Polinizaci6n por DePartmento Rio ob.".t"d". "t "l ,n. de Venezuela' Rio Mawarinuma, respectiva- Ven- "."urubuio. y abejas fue encontrada' Nesro. Territorio Federal Amazonas' los resultados es -""t". E'f .ignifi"u"o taxon6mico de ""o""lu (00"50'N; 66"10'W)' The altitude floral, morfologia del polen' y el air"",iat. Aiatomia was 140 m. Both sPecies were common ;" las bricteas pedunculares es considerado' ;;J in seasonally-flooded forest along the river (Figs. 1,2i. Inflorescence morphology' The neotropical iriarteoid major group development, and insect vrsltors were of palms is divided into two alliances Ld between 15 FebruarY and 13 (Moore lg73).The lriartea alliancecon- obr"rl March 1984. Palms, or adjacent obser- ,irt, o{ four genera, Socratea, Iriartea' vation trees, were climbed using climbing Iriartella, ^rrd'Di"tyo"oryum' It has been spikes (Ets Lacoste. 24160 Excideuil' susgestedthat the differencesbetween taxa F'rance). Herbarium specimens of each in"ihis alliance are insufficientto merit sDecieswere collected, and are deposited senericseparation. Macbride (I960) con- in NY u.ta VEN. A photographic record lid"r"d thit Sotratea-lriartea' and lriar- of inflorescence development was made' tella wete so alike that they should be (1965' Representative specimens ol Lnsecl vtst- united in one genus.Wessels Boer tors were preserved in alcohol' i972) also thought that the generawere little different, and reduced all four mem- bers of the alliance to a single genus' Socrateaexorrhiza: Iriartea. Moore (1963) disagreed with tnflorescence MorPhology' Macbride, and emphasizedthat there were DeveloPment,and sienificant differences which would be lnsectVisitors obscuredbY such a reduction' The inflorescence consists of a pedun- Until now little was known concernmg cle, up to 35 cm long and 5 cm diam', inflorescence morphology, development' HENDERSON:POLLINATION 65 .il Neblina' Socratea exorrhiza growing along the Rio Mawarinuma near Cerro de La PRINCIPES [Vor. 29 3. Inflorescence btd of Socratea exorrhiza after 2, Iriartea oentricosagrowing along the Rio leaf abscission. Mawarinumanear Cerro de La Neblina. and oval in cross-section,and coveredwith light stisma. Peduncle, rachis, rachillae, brown trichomes. The peduncle bears a floie.t are all ivory-colored. buds elongate prophyll and five thin peduncular bracts, Developinginflorescence leaf- i""gi"g from l0 cm to 60 cm long. The vertically within their enclosing is only appar- t""hitl. approximately15 cm long, and sheaths,and the lowest bud of the crown- bears up to I5 unbranched rachillae, each ent as a swelling at the base dies its sheath 30-40 cm long, covered with translucent shaft. When the lowest leaf the bud and trichomes. The rachillae are densely cov- splits from the base opposite vertical, dorsi- ered with triads of a central pistillate and a-bscises.This reveals the bud. It is two lateral staminate flowers, except for ventrally compressed,lanceolate by its the distal l0 cm which bear only stami- tightly enclosedat this time Prophyll The bud nate flowers. On some inflorescencesthe und hn" peduncular bracts. position for the distal 10 cm is separatedby a short sec- remains in this state and abscission(Fig' tion of rachillae, 2 cm long, which bears next 48 hours after leaf are closely no flowers at all. Staminate flowers have 3). Inside the bud the rachillae staminate and a 3-lobed calyx, the lobes are 2 mm long, pressedtogether, but both Flow- and three free waxy petals, l0 mm long' pi"tilut" flowers are fullv developed- interlock with Stamen number ranges from 65 in prox- irt ott adjacent rachillae have their imal flowers to 17 in distal flowers. Pistil- each other. Staminate flowers bv internal late flowers have three imbricate sepals, petalspushed apart and "oCl"d are clearly 4 mm long, and three imbricate petals, 5 p."t.*", so that tle stamens have their mm long, and a short, sessile 3Jobed visible (Fig. 4). Pistillate flowers HENDERSON:POLLINATION [: J I":4' ir.r* during day Inflorescence bud of Socratea exorrhiza wilh 5. Inflorescence of Socratea exorrhiza are : -ncular bracts removed. Note stigmas of pistillate between pistillate and staminate anthesis. Beetles :orvers just visible between staminate flowers. crawling over flowers. .rmas exserted, so that they are just vis- inflorescence, and crawl into the center e projecting between their two lateral among the rachillae, through the opening .minate flowers (Fig. ). Stigmas at this formed by the bracts. These Coleoptera r:re are white and covered with glistening were mostly Nitidulidae and Curculioni- :,rjections, and are presumably recep- dae. On one inflorescence,at 0900, the followingwere collected: of the 48 Towards the second evening 2450 Phyllotrox sp. ur vertical period the peduncle begins (Curculionidae, Derelomini) nightfall bend through 180o, so that by 4700 Mystrops spp. :.e bud lies parallel to the trunk, pointing (Nitidulidae) 2, possibly3, species ,rrn. The prophyll and three Proximal L45 Phloeonomussp. :acts split abaxially as the peduncle (Staphylinidae,Omaliinae) while the rnds, and remain erect, Unknown genus -'maining two distal bracts still enclose (Staphylinidae,Aleocharinae) the peduncle does, :.e bud. fhe bendlng of Numerousmites Rftinoseiussp. r\r€v€r' cause these remaining two bracts (Acari, Gamasina,Ascidae) , separate partially from the peduncle, :,us forming an entrance to the rachillae By morning the remaining two bracts have rd pistillate flowers at anthesis. Also at fallen from the inflorescence.During the :iis time the inflorescence gives off a following day the rachillae stay closely :rusty, fruity odor. During the following bunched(Fig. 5). Stigmasare brown and .:sht numerous Coleoptera arrive on the no longer receptive. The beetles contin- PRINCIPES [Vor 29 up to 60 rachillae, each uP to 120 cm lone. and densely covered with woolly tri- "ho"-".. The proximal ten rachillaebifur- cate at their junction with the rachis (Fig' 6). The rachillae bear spirally arranged tiiads of a central pistillate and two lateral staminateflowers, except for the distal 20 cm which bear only staminate flowers' Staminate flowers have three free sepals, 2 mm long, and three free Petals, 5 mm Ions. Stamen number ranges from 1l to l3]Pistillate flowers have three imbricate seoals.2 mm long. and three imbricate oeials. 4 mm long, and three sessilestig- inas. Peduncle,rachis, rachillae, and flow- ers are all ivorY-colored. Immature inflorescence buds are enclosed by the crownshaft at first, but most of their developmenttakes place free from the leaf sheath, and the small buds are clearly visible on the trunk' They elongate horizontally at first, eventually ",lrrrtg downwards(Fig. 2). The prophyll 6. Inflorescence oI Iriartea uentricosa s}rowrng and l4 peduncular bracts are deciduous, bifurcated rachillae. trichomes. and staminate flowers falling proximally from the peduncle as it at anthesis. "lorre"ut"t. When the last bract falls, the ,ach"illaebecome visible, and hang straight trunk. At this time ually crawl over the inflorescence' appar- down parallel to the begins. No particular entiy eating the trichomes on the rachil- staminate anthesis opening was apparent, lae.-Numeious small flies and bees also pattern of flower flowers were randomly visit the inflorescence during the day' Sta- iut rather, open inflorescence' Only one minate anthesis takes place the following dispersedon the opened at any one time' night, starting with those flowers inside the flo*er per triad in sticky yellow masses' inflorescence. By early next morning most Pollen was shed adhered to the rachilla staminate flowers have fallen, and all bee- and often these anthesiscontinued tles have left. trichomes. Staminate for a period of at least ten days, although lriarteaventricosa: indiviiual flowers were short-lived, and Inflorescence Morphology' quickly fell from the inflorescence'During DeveloPment'and this time numerousbees, belongingto a lnsectVisitors soeciesof Trigona. were observed col- fiom the anthers'Other less The inflorescenceconsists of a pedun- lecting pollen visitors were halictid bees,vespid cle, up to 30 cm long and 7 cm diam', f."qnJtt syrphid flies. Pistillate anthesis round in cross-section,and densely cov- wasps,and all staminate florsershad fall- ered with short brown trichomes' The beean after flowers became receptive pedunclebears a prophyll and 14^woody "rrl l.,diuiduul and dropped the inflo- peduncularbracts, ranging f1o1-9 cm.to sequentially, -from '230 Pistillate anthe- "* long, and 5 mm thick' The rachis ,"r""n"" if not pollinated. for at least fir-e davs' Bees is approximately 25 cm long, and bears sis continued rB5l HENDERSON:POLLINATION 69 rf the same species of Trigona wete case of Socratea and,Iriartea the differ- ,teerved visiting inflorescencesat pistil- ences appear major rather than minor. ;te anthesis,but in fewer numbers. Two other aspectsof thesepalms should also be considered in relation to pollina- tion; pollen morphology and floral anat- Discussion omy. Thanikaimoni (1970) described Correlation of inflorescence morphol- Socratea exonhiza.