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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