Palm Key

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Download Printable Palm Key

Iriartea is a subcanopy species that can reach 30 m in height.

Key to the most common species of palms (Arecaceae) at the La Selva Biological Station

The following key, based on stem, leaf, and inflorescence traits, can be used to identify 17 of the 33 species of palm found growing at the La Selva Biological Station. Links for each species will take the user to representative photographs of the important identifying characteristics of the species. As with the Plant Family Matrix, once some basic terminology has been mastered, the key should prove to be user-friendly. The key can also be printed out for use in the field.

Palm leaves come in three basic shapes: palmate (fan-shaped), pinnate (feathery), or simple. Palmate leaves are plicate, or folded like a child’s paper fan. At the point where the folds come together and join the petiole, palmate-leaved palms have a ridge-like structure called a hastula. Pinnate leaves usually begin life as a simple blade that subsequently splits into multiple leaflets (pinnae). An extension of the leaf stalk (petiole) known as the rachis holds the pinnae together. Pinnate leaves can reach enormous lengths (6 m), such that falling palm leaves are a major source of mortality for tree seedlings and saplings! Simple leaves are almost always split or forked at the tip and resemble the tail fin of a fish. Over time many simple leaves will develop tears and begin to resemble pinnate leaves.

Palm inflorescences consist of branched or unbranched spikes bearing clusters of many flowers. Usually the tiny flowers will be single sexed and an inflorescences will consist of clusters of separate male and female flowers, making the plants monoecious. The inflorescence is subtended by a leafy or woody spathe that often falls off as flowering progresses. Fruits are either fleshy berries with a single seed or covered by a hardened coating and resemble a miniature coconut.

Palms range in stature from understory species that rarely exceed 2 m in height, medium sized understory species that reach 5-6 m in height, to subcanopy species that may reach 25-30 m in height. Understory species often appear to lack stems (acaulescent). The trunks of subcanopy species often appear disproportionately skinny relative to their height. Many species are clonal (caespitose), consisting of clusters of upright stems that are connected to one another underground. Others are solitary or aclonal, consisting of a single stem or in some cases a cluster of leaves with no apparent stem. Stems often bear circular scars left behind by shed leaves. Some species are covered with fierce spines that should be avoided, as contact can result in puncture wounds that frequently become infected. Two species have large well-developed aerial or stilt roots and lack a true trunk at the base of the tree, while a few others have much smaller stilt roots that originate close to the ground.

Palms at La Selva can be divided into five groups:

I. Palms with palmate (fan-shaped) leaves and spines on the trunk.

II. Palms with numerous well developed (0.5-3 m long) stilt roots.

III. Palms, clonal or solitary, with pinnate or simple leaves and spines along stems.

IV. Clonal palms lacking spines.

V. Solitary palms lacking spines.

I. Palms with palmate (fan-shaped) leaves and spines on the trunk.

Cryosophila is the only species at La Selva with palmate leaves.

Scientific Name	Stature / Stems	Leaves	Inflorescence, Flowers, Fruits	Notes
Cryosophila warscewiczii	Subcanopy to 10 m tall Solitary Abundant branched spines on trunk	Palmate with hastula “c” at tip White undersides	Infl branched Fr white fleshy	Spines originate from roots to trap leaf litter Only palmate sp!

II. Palms with numerous well developed (0.5-3 m long) stilt roots.

Socratea and Iriartea are best separated by density of the cone formed by the stilt roots.

Scientific Name	Stilt Roots	Stature / Stems	Leaves	Inflorescence, Flowers, Fruits	Notes
Socratea exorrhiza (S. durissima)	Well developed 1-3 m long Spiny Open cone	Subcanopy to canopy 30 m tall Prominent crown shaft	Pinnate 3 m long Ragged edges Terminal leaflet split	Infl below crown shaft Infl erect in bud Infl branching To 60 cm Fr yellow	Spider and capuchin monkeys feed on fruit pulp. Hard wood.
Iriartea deltoidea	Well developed 1-2 m long Not spiny Black Dense cone	Subcanopy to canopy 30 m tall Prominent crown shaft Stem swollen in middle	Pinnate Ragged edges Terminal leaflet not split	Pendant bud resembles bull’s horn Infl below crown shaft, hanging, multiply branched, cream colored, to 1.5 m long Fr blue-black

III. Palms, clonal or solitary, with pinnate or simple leaves and spines along stems.

Take notice of whether or not the palm is clonal (clusters of stems), leaf shape (simple vs. pinnate), inflorescence branching patterns, and locations of spines.

Scientific Name	Clonal	Stature / Stems	Leaves	Inflorescence, Flowers, Fruits	Notes
Bactris coloradonis (B. porschiana)	+	Understory 8 m tall Straight stem Ring of spines at leaf scar Spines round	Pinnate Leaflets spiral, separated, irregular Spines on midvein & margins	Many branched infl Fr orange-red	Often solitary Dense wood used for xylophone keys “Bactrum” = king’s stick
Bactris hondurensis	+	Understory 3m tall Few stems Spines often black or black tipped	Simple Small spines along margin Light green undersides due to white hairs Spines along midrib	Infl 3-7 branches Spiny spathe Fr orange-red	Only palm with simple leaves & spines
Astrocaryum alatum	-	Understory 2-6 m tall Spines on persistent petiole bases, but not on trunk	Pinnate Leaflets in a single plane Underside of leaves light green to white Flattened spines on petiole	Fr spiny	Swamps
Astrocaryum confertum	-	Subcanopy to 20 m Flattened spines	Pinnate Petiole and rachis spiny Leaflets in multiple planes	Infl branched Fr star-shaped Ovoid seeds with 3 pores	Only spiny solitary canopy palm.

IV. Clonal palms lacking spines.

Take notice of the clustering of stems, size and shape of leaflets, and branching patterns of the inflorescence. Don’t be fooled by clonal palms with a single stem.

Scientific Name	Stature / Stems	Leaves	Inflorescence, Flowers, Fruits	Notes
Geonoma congesta	Understory 5 m tall Clusters of 10-20 green stems Petiole scars	Irregularly pinnate 1.5 m long Tip split Mid-vein raised, sharp, with bump	Infl branching w/ 3-5 fingers Stalk orange Ripe fr black
Synechanthus warscewiczianus	Understory 5 m Stems green, ringed	Pinnate Irregular Leaflets of varying width Petioles round Crushed leaves dry black	Drooping bottlebrush infl below leaves Fr orange-red “jellybean” Seeds brain-like	Prop roots sometimes at base
Prestoea decurrens	Medium sized 6 m Stems round green Pink prop roots at base	Pinnate Leaflet tip sharply pointed, twists to form pocket	Infl 10-70 branches Fr black	Along streams and rivers Dispersed by currasow

V. Solitary palms lacking spines.

Species are distinguished by stature (understory vs. reaching for the canopy), leaf shape (simple bifid like the tail fin of a fish vs. pinnate with many leaflets), leaf size (medium vs. huge), location of inflorescence, and branching patterns of the inflorescence.

Scientific Name	Stature / Stems	Leaves	Inflorescence, Flowers, Fruits	Notes
Geonoma cuneata	Understory 1.5 m tall	Simple bifid, Not split (usually), wide, thick, strongly pleated Base wedge-shaped, looks squeezed Petiole short New light green	Inf single spike to 1 m Originates from side Fr green, yellow-orange, black Stalk purple	Most common Geonoma sp
Asterogyne martiana	Understory 2 m	Simple bifid Ferrugenous (rusty) coating at base Young yellow-orange	Inf originates from tip of stem 2-7 branches Fls white, tiny star-shaped Sweet smell Fr red – purple-black	2nd most common understory palm Bats use leaves for tents Wasps and bees pollinate
Calyptrogyne gheisbreghtiana	Understory 2 m tall No stem	Paper thin Split unevenly Assymmatrical base	Infl single spike Ringed scar left by spathe Garlic odor	“Cup flower” Swamps Pollinated by bats
Chamaedorea spp.	Small to medium 3-5 m tall	Pinnate Sigmoid leaflets Yellow line along petiole Similar to Synecanthus Crushed dry black	Branching infl	“Parlor Palms”
Euterpe macrospadix (E. precatoria)	Subcanopy 25 m Tall with skinny stems Orange stilt roots at base	Pinnate to 4 m long	Inf below leaf sheath Many branches facing upward in fl Fr purple-black
Welfia regia (Welfia georgii)	Subcanopy 25 m tall Rings on stem Stems orange Young plants lack stem	Pinnate V. large to 6 m long Wide leaflets Young leaves deep reddish brown	Huge hanging antler-like infl to 40 cm Fallen infl resemble snakes! Fruit brown almond-sized	2nd most common tree at La Selva Rodents eat fallen seeds

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