Pollination of Amazon palms

(Arecaceae)

Plantensystematiek   28 juni 2003

door: sander van Andel

docent: Lars Chatrou

Index

Abstract

Introduction

General description of Palms

- morphology

- genera and species

- economic uses

Palm inflorescence

Different ways of pollination of palms

- cantharophily

- mellitophily

- myophily

- Anemophily

Table 1 arthropods associated with palm subfamilies, tribes and genera

Abstract

Introduction

Because of the importance of palms to man there are numerous historical references of palms and there pollination. For example the necessity of cross-pollination for the dioecious genus Phoenix of the subfamily Coryphiodeae (date palm) was even understood in classical times. In the Assyrian art you find symbolism of artificial pollination of their date palms crops (Henderson, 1986).

Another foreseeing vision was the opinion of the Victorian naturalist J.G. Wood who wrote “The hidden virtues of weevils (beetles) have yet to be discovered. That such virtues exist there can be no doubt” (Wood, 1874). His optimism is rewarded by the relative recent knowledge that among there hidden virtues can be counted the importance in the pollination of palms (Moore 2001).

Palms have a number of the characteristics associated with anemophily(pollination by wind) such as reduction of attractive flowers parts, limited nectar production and an immense production of pollen (Bertin, 1989). But other ecological characters described by Whitehead like ecosystem domination, coordinated flowering and short growing seasons (Whitehead 1983) are not associated with anemophily. Arguments for entomophily are the relatively larger nutritional pollen grains with spins and sculptured surface. (fig. 2) The success of angiosperms owes a great deal to entomophily (insect pollination)(Pellmyr et el., 1991) and its development in some of the palms has led to great diversity of pollination mechanisms.

The review by Henderson (1986) leads to the conclusions that palm pollination is dominated by entomophily manifested in three syndromes cantharophily(beetles), melliphily(bees) and myophily(flies). Anemophily does appear with palms but seems to be derived from when population slowly got isolated from pollinators. Evidence of a close association between certain beetles and palm may be indicative of ancestral cantharophily.

fig2: Nypa fruticans www.biodiversity.org.uk/ibs/

General description of Palms

Morphology

The general symbol of a palm is a large, aborescent, erect trunked tree with large leaves, which are pinnately or palmately compound with those, leaves situated in a rosette. However this is only one of many forms the palm family has.

Distinctive characters that united the family are having only one apical meristem, having a sheath at the base of the leaf and having a large spike inflorescence often accompanied by big woody spathe.

Distinctions between palms can be made on characteristics like height of an adult palm (large: over 12m, medium 6 to 12m, and less than 6m in height), leaf morphology and the presence or absence of a stem. With basal branching there are single or multi-stemmed species. In case of a stem further divisions can be made like erect, prostrate, climbing or subterranean. And interesting aspect of the stem is whether it armed or not armed and whether it is cylindrical or swollen (Kahn & Granville 1992).

fig3: www.anbg.gov.au/anbg/ glasshouse/

genera and species

There are about 200 genera and 2000 species worldwide, mostly in tropical and subtropical regions (Uhl &Dransfield, 1987). Henderson recognized 34 genera and 151 species in the Amazon region. Nineteen of these are considered species complexes, which are further divided into 57 varieties. This brings the total number of taxa to189. About 140 (75%) of these taxa are endemic to the Amazon region (Henderson, 1995).

economic uses

Despite relative few species palms are one of the most important economic plant families in the tropics. Palms provide many useful products that are often essential to the existents of people. All parts of the tree are used. Leafs have many uses like roofing, wax production and using fibbers for making baskets. The wood of trunks is used for building material and starch. The apical meristem is taken for the product of palm heart, which is considered as a delicates. Fruits of the palm family are very common like the coconut and the date. Palm oils, which are used for manly soap and candles, are also derived form fruits. Even roots are used for medicinal proposes (Kahn & Granville 1992)

Coconut (Cocos nucifera) date palm (Phoenix dactylifera)

www.bio.ilstu.edu/armstrong/ syllabi/coir/coir2.htm waynesword.palomar.edu/ ecoph10.htm

Oil palm (Elaesis Guineensis

www.alcomet.com.sg/

Palm inflorescence and flowers

The inflorescences of palms are very divers but this description is the most common. Palms have an inflorescence that is often enclosed by bracts (spathes) that might become woody at maturity. The inflorescence is often growing from the apical meristem. It can be simple to many-branched with different colors. The colors are often dull whitish or more orange reddish. (Moore, 2001) But against the green foliage of a dense forest this could be highly attractive.

The flowers are actinomorphic, generally small, and are bisexual or more often unisexual. The perianth usually consists of two whorls of 3 distinct or connate segments each, often distinguished primarily by size, the outer series or calyx being the smaller. The androecium consists typically of 6 distinct stamens in two whorls of 3 each but sometimes comprises up to several hundred variously connate or adnate stamens. The gynoecium is syncarpous or apocarpous. Syncarpous forms consist of a single compound pistil of usually 3 carpels, 1 or 3 styles, and a superior ovary with 3 locules, each containing a single basal, axile, or apical ovule. Apocarpous, forms consist of usually 3 simple pistils, each with a superior ovary containing one locule with a single basal to apical ovule. (Uhl & Dransfield, 1987)

To attract the pollinators the flowers have different mechanisms like smells and nutrient nectar. The flowers of palms often have rapidly growing tissues with nutritive value that attract the pollinator. But flowers with many pollinators also have a thick layer of

Chinees wind palm

www.floridata.com/ref/ t/t_fortun.cfm

Different ways of pollination of palms

Cantharophily

Pollination by beetles is called cantharophily. This syndrome is associated with the following phenomena (although there are exception to each): Inflorescence is ivory or cream colored, it has small staminate flowers and pistillate flowers mature at bract fall. The flowers are protogyny and they have pistillate flowers crowded on the rachillae that are enclosed by bracts during the short lived and nocturnal anthesis. The beetles than are attracted by a temperature elevation (from high metabolisme) and a musty odour. Following staminate anthesis is temporally Beetles of the family Nitidulidae and Curculionidae are considered the most important category of entomophily with the pollination of palms (Henderson, 1986). Other beetle-families such as Scarabaeidae and Staphylinidae are also considered of importance to the pollination of different palm genera.

Mellitophily

The second most important syndrome is that of bee pollination. Characters that are often associated with mellitophily are that the staminate and pistilatte flowers are coloured and developing after bract fall. The flowers are protandry and the staminate flowers are opening at dawn and falling at noon, they produce nectar and they have fewer stamen than the cantharophily staminate flower. The staminate anthesis is lasting for more than a week while the pistillate anthesis is short lived (2-3 days) and is temporally separated. Pistillate anthesis also has nectar production and sweet scent.

Myophily

- anemophily
Table 1. arthropods associated with palm subfamilies, tribes and genera

(derived largy from Henderson, 1986, and references therein). Copied from Moore (2001)

Palm subfamily and tribe	Palm genus	Insects associated with palm flowers and floral characteristics suggestive of entomophily
Coryphoideae
Corypheae	Chelyocarpus	Odour probably attractive to beetles
	Cryosophila	Derelominus sp.; Mystrops sp. Strong lilac smell. Inflorescence temperature elevation
	Itaya	Trigona sp. Bees dominate. Beetles and flies also important
	Thrinax	Beetles and thrips on Thrinax excelsa. Pink, scented flowers
	Rhapidophyllum	Visited by Notolomus sp. (Derelomini). Flowers may be brightly coloured with dull bracts. Musky odour, especially from male flowers.
	Chamaerops	Two pollen-eating Derelomus (beetle) species recorded. Chamaerops humilis sometimes secretes nectar.
	Rhapis	Derelomus ueoni (beetle) breeds in Rhapis excelsa
	Livistona	Nectaries present
	Johannesteijs- mannia	Different species have flowers, with odours ranging from sweet to sour. Nitidulid and staphynilid beetles, flies, thrips, ants and termites probably involved in unspecialized pollination.
	Licuala	Nectar secretion.
	Pritachardia	Flowers visited by bees, wasps, and other insects. Nectar secretion in Pritchardia martioides and Pritchardia rockiana.
	Serenoa	Notolomus sp. (Derelomini) (Beetle) and Exoprosopa fascipennis (Bombyliidae) (bee flies) found on inflorescences.
	Corypha	Chrysomyia spp., (fly) (Diptera: Calliphoridae). Yellow flowers, odour offensive or of sour milk. Sepal nectaries.
	Sabal	Sabal palmetto visited by a range of insects, initially bees and flies, later by Coleoptera and Lepidoptera. Apis mellifera, although exotic, thought to be the major pollinator. Continuous nectar and odour production through the day. Sepal nectaries
Phoeniceae	Phoenix	Apis mellifera attracted to Phoenix reclinata and many bees to Phoenix caespitose. Male flowers scented and nectaries possibly present
Borasseae		Sepal nectaries
Calamoideae
Calameae	Eugeissona	Visited by a wide range of arthropods. Trigonid bees visit male flowers. Alcoholic smell resulting from fermentation of nectar.
Palm subfamily and tribe	Palm genus	Insects associated with palm flowers and floral characteristics suggestive of entomophily
Calameae	Salacca	Derelomus spicies (beetle)on male flowers of Salacca zalacca before visiting females, where they feed on nectar-like material. Females oviposit in female flowers, leaving the next day.
	Daemonorops	Musty odour, crowded flowers, many beetles present.
	Clamus	Musty or sour odour, crowded flowers, beetles, wasps and flies
	Calospatha	Musty odour, crowded flowers, many beetles present
	Ceratolobus	Penetrating odour. Staphylinid beetles, ants, thrips and Lepidoptera (butterflies) recorded on Ceratolobus glaucescens. Inflorescence enclosed except for small slits to let pollinators through.
	Plectocomiopsis	Fragrant odours
	Pletocomia	Fragrant odours. Visited by insects, especially weevils (beetles).
Nyopoideae	Nypa	Visited by Trigona spp. (bees) And flies of the Drosopilidae. The bees were rarely found on female flowers, and the flies carried significant quantities of pollen. Dipteran larvae and occasional beetle larvae bred in the female flowers. Flowerbuds brightly coloured, pollen orange and sticky and flowers with a distinct odour.
Ceroxyloideae
Cyclospatheae	Pseudophoenix	Many bees attracted by nectar.
Ceroxylyeae	Ceroxylon	Many melyrid beetles found on male flowers of Ceroxylon mooreanum.
	Ravenea	Curculionid and nitidulid beetles visit Ravenea louvelii and Ravenea dransfieldii. Inflorescence heating occurs and musty aroma. Other species, e.g. Ravenea sambiranensis and Ravenea madagascariensis, probably bee-pollinated.
Hyophorbeae	Hyophorbe	Intense fragrance, bright orange flowers and sepal nectarines.
	Synechanthus	Male flowers of Synechanthus warscewiczianus visited by many drosophilid flies, which later visited female flowers.
	Chamaedorea	The bees of Trichona tataria and Cholus spp. weevils visited the flowers of Chamaedorea wendlandiana, but only the former were recorded as having carried pollen. Visitors to other palms include troigonid and halictid bees, chrysomelid beetles and drosophilid flies. Many palms of this genus have a highly scented, brightly coloured flowers, with sticky pollen.
Palm subfamily and tribe	Palm genus	Insects associated with palm flowers and floral characteristics suggestive of entomophily
Arecoideae
Caryoteae	Arenga	Apis mellifera visit scented male flowers of Arenga tremula. Sepal nectaries.
Iriarteae	Iriartella	Ants visit inflorescence
	Iriartea	Iriartea ventricosa and Iriartea gigantea visited by Trigona sp, bees. Melipona and Apis species also recorded. Beetles of secondary importance.
	Socratea	Socratea exorrhiza considered beetle-pollinated and visited by large numbers of Phyllotrox sp. (Derelomini) and Mystrops spp. (Nitidulidae), including M. basalis, M. dufaui and M. corpulentus. Sepal nectaries in S. exorrhiza.
	Catoblastus	Phyllotrox sp. and Mystrops adustus on Catoblastus kalbreyeri.Beetle
	Wettinia	Mystrops basalis, Mystrops teapensis, Pyllotrox sp.,flies and bees on male flowers of Wettinia hirsute.
Podococceae	Podococcus	Sepal nectaries
Arecea
	Manicaria	Larvae probably breed in the flowers. Inflorescences with netlike bracts, with restrict entry of insects larger than pollinating nitulid beetles.
	Leopoldinia	Scented male flowers
	Dypsis	Bee pollination in some Dypsis spp. Others have tiny, specialized flowers for small pollinators not yet studied.
	Euterpe	Bees visited male and female flowers. Petals purple and nectar-like substance produced. Beetles of secondary importance.
	Prestoea	Prestoea decurrens visited by Trigona, Neucorynura and Lasioglossum species bees and one species of halictid bee. Small flies may also visit.
	Hyospathe	Few insect visitors, mainly ants, beetles and bees.
	Archontophoenix	Trigona amalthea, bee, considered major pollinator of Archontophoenix cunninghamiana.
	Rhopalostylis	Flies (mainly) attracted to exudates of male and female flowers.
	Calyptrocalyx	Sweet scent, nectar produced.
Palm subfamily and tribe	Palm genus	Insects associated with palm flowers and floral characteristics suggestive of entomophily
Arecea	Ptychosperma	Ptychosperma macarthurii is visted by Trigona, Nomia and Homalictus species bees and flies of the Syrphidea Calliphoridae and the Drosophilidae. Nomia sp. considered most important pollinator. Nectar secreted, pollen heavy and sticky.
	Hydriastele	Bees of the genera Nomia, Homalictus and Trigona visited male flowers and collected pollen, But did not visit receptive female flowers. Drosophilid flies visited but considered unimportant. Nodocnemus spp. weevils (Derelomini) present. Musky odour of flowers and white sticky pollen.
	Nenga	Nenga gajah has marked odour and is visited by nitulids and trigonids
	Pinanga	Nitidulids and curculionids beetles present on flowers Pinanga coronata. Musty odour
	Areca	Pollen of Areca catechu collected by bees and other insects, which did not visit female flowers. Sweet-scented flower.
	Iguanura	Male flowers attracted ants, flies, bees, wasps and weevils. Fewer insects visited the female flowers.
	Marojejya	Inflorescence structures similar to those of palms known to be beetle pollinated
Cocoeae	Butia	Butia leiospatha pollinated by bees, waps, flies and curculionid and nutulid beetles
	Cocos	Cocos nucifera inflorescence are visted by many insects, but only a few are common to both male and female flowers. Derelomorhus eburneus, apparently restricted to coconut flowers, may be an important pollinator. Nectaries present an flowers sweetly scented. Apis mellifera bees considered important in many areas.
	Attelea	Beetle-pollinated
	Syagrus	Beetle or bee pollinated predominates
	Orbignya	Mystrops spp. found in numbers on Orbignya Martiana flowers. Scented with nectaries.
	Maximiliana	Maximiliana martiana visited by Melipona sp. bees
	Barcella	Barcella odora flowers are sweetly scented and visited by bees, flies and wasps
	Elaeis	Insect pollination important, especially Elaedobius spp., beetles, (curculinids) . Female flowers strongly, but intermittently, scented
	Acrocomia	Curculids, nitulids and scarabs (beetles) implicated in pollination
	Aiphanes	Bees, flies and beetles implicated, depending on location
Palm subfamily and tribe	Palm genus	Insects associated with palm flowers and floral characteristics suggestive of entomophily
Cocoeae	Bactris	Bee and beetle pollination important. Flowers with musky odour. Scarabs important
	Astrocaryum