Palm Key
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Download Printable Palm Key
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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