Is a palm tree not a tree? In categorizing plants and animals for the Everglades Ark Epicollect5 data base I was conflicted in assigning the characteristics of trees to palms. I have called them palm trees forever but they really look different from oak, olive or other trees. Checking out the definition of a tree resulted in an ambiguous answer.

Featured image: In a spin about palms

Definition of tree: From a technical standpoint, palms fit American Forests’ current definition of trees, as they are woody plants with an erect perennial stem or trunk, at least 9.5 inches in circumference at 4.5 feet above the ground. They also have a definitively formed crown of foliage and a height of at least 13 feet. 

This still didn’t satisfy my curiosity. I still wondered why they were so different. Here are photographs of tree aspects to show the physical differences:

Tree landscape view

Leaf patterns

Photomacrograph leaves

Photomicrograph of leaves

Common biology of both di and mono cotyledonous plants. Both have chloroplasts for metabolism and stoma

Tree roots

Tree cross sections

Tree behavior to injury

Flowers

Here is a list tabulating differences in the characteristics between the tree types.

Aspects:	Palm	True tree
Roots	shallow multiple small distributed	deep, branching with tap root
Trunk	the trunk is actually the stem which bends	thick, rigid
Branches	no branches	multiple arborizations
Leaves	veins begin at the base, run parallel to the length of the leaf, stoma on upper leaf surface	central veins with multiple arborizations to leaf periphery, stoma on lower side of leaf
Outer surface	stumps of old growth leaves, no structured interior wood	specialized bark covering wood
Trunk core	fibrous without annular rings	woody, highly structured interior nutrient flow system
Interior structure	fibrous with layered leaves	organized circulatory system, annular growth rings
Recovery	cannot repair injury or disease	can heal wound and fight disease
Development	monocotyledon	dicotyledon
DNA	Grass	Tree

A palm tree is really a palm grass.¹ They are monocotyledons. Genetically they are similar to other grasses like bamboo. They are resistant to storm damage fracture because of their lack of a woody interior structure but are more subject to uprooting because of their shallow roots.

Grasses are flowering plants that are members of the monocot class that also include corn, rice, lilies, orchids and palms. Now that I understand what a palm is I can more freely post palm types, flowers and fruits. Later I will show the microscopic view of tree anatomy pointing out differences between monocots and dicots.

This subject opens a wide spectrum of ideas regarding plants. We have already broached the idea of cotyledons. There is much more to explore including the microscopic examination of cross sections of plants and their appendages or stems, roots and flowers as well as angiosperms vs gymnosperms and the role of sexual vs asexual reproduction and seed development.

The micrographs shown here are all done with simple direct bright field and transmitted light. Just wait until we get into cross sectional, stained, transmitted plane, and polarized light illumination!

The Epicollect5 database will be modified to reflect this altered view of classification.

1. References:

Dicot vs monocot

Palm leaf anatomy

Plant vascular system

Plant leaf anatomy

#tree #palm #monocot #dicot #monocotyledon #dicotyledon #veins #stoma #annular rings #reticular veining #petals

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