Inside of a Palm Tree - Roots, Trunk and Fronds

Anatomy of a Palm Tree: Understanding the Structure

INTRODUCTION

From the winding root system, then along the trunks - with all their varieties. Ending up in the leaf crown, with the structure of the fronds.

We were amazed to find the uniqueness there, inside of a palm tree. When we first learned this stuff! But maybe if you first need to step back and see the full picture before focusing on anatomy - start with What is a Palm Tree.

Like quite no other plant! We think you'll be amazed, too. If you’re curious how palms developed their uique features, continue with The Origin of Palm Trees to see how far back their story goes.

Parts of palms have exact purposes. Looking inside, you'll see the uniqueness the structures inside of a palm tree have. Crucial for a palm's growth & survival.

Close Look Inside a Palm's Roots

Various parts of a palm tree's roots begin their specialized action. Let's trace how that happens. Notice it first begins with the sprouting palm seed.

THE SEED GOES INTO ACTION

A newly planted palm tree seed has only one embryo, the one seed leaf. That's the inactive part of the seed that's ready to begin it all. It soon begins growing a starter root.

The seed sends out a sprout, forming the start of the root.

Not long after that, the Root Initiation Zone forms. It replaces that first sprouted root. Shaping itself at the stem's base.

Then depending on the Palm Species, extending a bit upward into the lower trunk.

Root Growth

Adventitious roots gow out from the stem. Adventitious means they're not growing from a plant's typical area.

These roots begin growing out at their full width. As you'll learn about the trunk, palm roots don't have secondary growth. The initial girth is as wide as they'll ever get.

They branch to three levels, though. Each somewhat thinner than the one before.

Palm roots can spread outward widely.

They anchor the palm firmly in the ground. Yet compared to woody trees, palm roots are somewhat shallow. Unlike a Palm Parts above ground, roots can regrow.

• If cut when transplanted. New roots form above the cut.
• The Root Initiation Zone can generate more adventitious roots.

Undermined roots visible in this toppled over palm by sand erosion on a shoreline

Palm Roots Bring Food

Root design is also kind of different, for a palm's nourishment. As opposed to woody trees, palm's primarily feed from the ground's upper soils. That's why we all know palms generally need regular watering.

• None produce root hairs. 
• The task of the thinnest 3rd branch of roots is absorbing water & nutrients.
• The inner trunk's nourishment bundles have connections to the roots.

Other Palm Tree Root Varieties

Some palms develop roots above the soil.

Stilt roots are a palm support system in some that grow in tropical rain forests.

Iriartea deltoide - This palm's rop roots develop over time. So they're not seen When it's young.

The Root Initiation Zone extends into view on some Date Palms. As they age, aerial root stubs can be seen at the trunk's bottom.

Aerial roots emerge on some palm species when they're older.

Second level roots of some palms can absorb oxygen. They're called pneumatophores.

• Particularly in those palms of swampy environments. The soil there can't easily access the O₂.
• Some even grow aerial roots called pneumatorhizae, which can absorb oxygen. 
• The inside of a palm tree's pneumatophore has areas that seem to work like human lungs! Conducting gas exchange.

Inside of a Palm Tree Trunk

Palms grow with a single treelike trunk (also called stems). But also they can take a shrub-like form, with many trunks coming from the roots.

Surprising to many, trunks can grow vine-like. Climbing upward using another plant for anchoring.

Only the genera Hyphaene & Nypa produce branching trunks.

Whichever way they grow, the inside of a palm tree trunk will be the same. Although there are many styles to the trunk's outer covering. Which is not bark.

Palms aren't actually true trees. Their trunk functions are quite different from woody trees of forests & meadows. Like an oak, birch or spruce. These forest tree species have an inner network to get their nourishment. Compared to blood vessel networks in humans.

Once you’ve seen what’s going on internally, it will help to compare that with the Characteristics of a Palm Tree.

Palms Don't Have the Pathways Like Woody Trees

Instead of a network, palms have separate bundled parts inside the trunk.

They're scattered through the trunk and also the stems (petioles and rachis). These bundles use conductive tissues & tons of separate vascular strands. They transport water & nutrients throughout the plant.

This uniquely palmy system inside of a palm tree is its lifeblood.

Palm Trunk's Insides Make Things Different

Because of the inside of a palm tree trunk's structure, palm processes are distinctive.

PALM TRUNK'S YOUTH

• A trunk's first growth works on a minimal upward reach. Providing new growth of leaf bases protecting the palm's heart.
• At the same time it mostly works on reaching its greatest width. 
• Once achieving that, it completes what's called the Establishment Phase. Then it begins growing further upward.

The "Syrup Palm" - Gaining width in its youth.

GROWING UP

With aging, inside of a palm tree trunk gets more solidly strong at the edges.

• Palms don't increase their trunk width by growing new wood, as secondary growth. In other words, they don't get thicker by forming yearly growth rings.
• As they age, all trunks and stems basically stay the width they first grew to in youth.
• Only sometimes, trunk bulges happen by swelling of individual inner cells. Or cell shrinking inward. This results from the lengthy effects of rain deluges or extended drought.
• Changes in trunk width aren't caused by adding new cells.

Jubaea chilensis (Syrup Palm) can top off at 78ft/23.8m tall.

NOURISHMENT EFFECTS

As a Monocot Palm, the little nourishment packs that grow inside of the palm tree trunk are a predefined (finite) number. So...

• Once the palm gets to its tallest at maturity, no more nutrient packets are supplied.
• Those already there can't multiply. Inside the palm trunk, the plant won't produce any more.
• And if any get damaged or die, there is no method to repair or replace them. 

Hardened cells are left over from the bases of previously shed fronds. Forming a Palm's outer protective layer, that's not bark.

EFFECTS OF NO SECONDARY GROWTH

Secondary growth means...

• A tree or bush gets thicker around, as it's growing taller. A woody tree trunk gets wider and wider each year, adding a new layer of wood like another ring on a bullseye.
• If a tree trunk is injured, this special layer makes new wood and new bark. It slowly grows over the wound like a bandage.

Palms do not have secondary growth. That affects them in certain ways.

• During the establishment phase, they're at their most unstable time. If anything goes wrong, it will be difficult to overcome.
• Continued growth & life depend on the growing point (heart or meristem), inside the trunk. 
• If serious injuries happen to a trunk's meristem, there's no healing it. That results in death.
• Grafting cannot work on a palm trunk.

Inner Workings of Palm Leaves

How important are the insides of palm tree leaves?! They have a specialized structure made for capturing sunlight. Producing food in their cellular photosynthesis factories.

The basics of photosynthesis, where light, water & CO2 create oxygen.

The newest true seedling leaves (eophylls) don't look at all like their adult form. They usually sprout with one (entire) seed leaf. Sometimes with two (bifid) leaves.

The first parts of a palm leaf (frond), are the sheath (base) & the petiole (stem).

The pinnate's sheath & petiole are reinforced for strength.

The palmate's sheath & petiole are reinforced for strength

These leaf stems are tube-like inside & have walls strengthened with masses of fibers.

• To endure weather stresses of the palm. While carrying water & nutrients to leaf tissues.
• Needed nourishment arrives at the palm's blade. Conducting tissues use it to supply food factories in the fronds. 
• Using sun energy for photosynthesis. Which creates carbohydrates to nurture continued growth in the palm. Making flowers & fruit.

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Inside of a Palm Tree Flower

Most palm flowers are extremely small, with muted coloring.

They all grow out on an inflorescence. Which is the usually long & branched stalk or stem for all the palm's flowers. Palm flowers are almost always closely set together. That's how palm flowers can look flashy along an inflorescence.

The structure of inflorescences can Help With Palm Identification. More details of the inner workings of palm flowering physiology are known. But really, much is unknown say notable botanists, still yet to be discovered.

What are Brachts?

BRACHTS are specialized leaves with a woody consistency. They protect young, growing inflorescences.

This male Phoenix roebelenii is a dioecious palm, Only male flowers will be found here. Note the brachts, which have now outgrown their usefulness for these flowers.

Palm Flower Genders

Flower structure in The World of Palms is quite variable. Palm flowers have three gender types. They can be arranged on palm trees in several ways.

• Female flowers only with the pistil.
• Male flowers only with the stamen.
• Bisexual flowers have both male & female reproductive organs. They're termed "perfect."

Palm Flower Arrangements

Palm flower arrangement also varies. A lot depends on if they're Monoecious vs Dioecious.

• Monoecious palms have both gendered flowers all on the same palm plant. Usually interspersed by gender groups along the inflorescence. With each gender active at different times. (Better for no intra-palm pollination!)
• Rarely genders are separated onto their own inflorescence.
• Dioecious palms have flowers of one gender only on a plant. Males on one palm, females on another. Like these...

Mediterranean Fan Palm or European Fan Palm

The Chamaerops humilis is Usually Dioecious - BUT FOR EXCEPTIONS!

Mediterranean Fan Palm with only female flowers.
Image ©Hans Hillewaert - Used With Permission

This Mediterranean Fan Palm has male & female flowers.

Palm Flower Parts

Male Flowers - The stamen contains reproductive organ parts.

• At the top is the anther. It's a little bag that contains pollen.
• The stem of the anther is called the filament. It supports the anther. Very long & very narrow to help attract pollinators.
• Pollination process begins here with the male reproductive parts.

Female Flowers - The stigma contains reproductive organ parts.

• The stigma is at the top of a stem. The outer layer is sticky, so pollen can easily attach.
• The stigma's "stem" is called the style.
• The style leads downward to the ovary, which contains ovules (typically three of these egg cells).

Palm Flower Pollination

Pollination happens when the male's pollen reaches & sticks to the female's stigma.

• A Pollinator Attracted to the Flower brushes against the male anther. Pollen sticks to the bee, ant, etc. 
• Palm pollinators are often insects. Wind also helps, & don't rule out hummingbirds!
• Pollinators then visits another flower (maybe on a different palm). Where the pollen gets stuck onto the female stigma. 

Scarab Beetle on Saw palmetto blossoms. Helps pollination. And later when it fruits, it's Bback for the eats!

Pollen sticks to the style.

Then works its way down the style, arriving at the female ovary. Starting the fertilization process, leading to fruit & seed production.

Inside of a Palm Tree's Fruit

Most Palm Tree Fruits are fleshy & contain one seed. With a thick covering around the inner seed. They're called drupes.

• If the inner seed covering is thin, then they're called berries.

For fruit botanic terminology, think of the term -carp. Coming from the Greek word Karpos, which related to mythology about bearing fruit.

• Peri- means around or surrounding, it's also in medical terminology. Pericarp means surroundings of the fruit.
• Endo- means inner for this case, so Endocarp is the inner part of the fruit.

Nypa fruiticans Seeds are Also Edible.
The palm itself has many uses for local communities.

Survival Strategy: The Secret to Palm Tree Resilience

The ways that the inside of a palm tree evolved gave them growth and nurturing capabilities.

But a side effect to this, was giving palms survival strategies. Helping them to thrive and continue growing in their endemic environments.

Their secret is how well palms stand up to strong winds. Well, let me stretch that a bit! As they won't stand up straight in behemoth wind storms. Like hurricanes or typhoons. I think you must've seen the photos of palms bending in a massive storm.

Some compare these side effects to reinforced concrete columns!

• The inside a palm tree trunk's central cylinder is built of a matrix of fibrous material. Compare it to poured concrete!
• Within that are the scattered nutritional bundles. They're very strong. Because lignin & cellulose continue depositing within them. For their entire lives. Compare these to steel rebar rods.

See the inside of the palm tree trunk to find there are no yearly growth rings.

The outer edges are stronger & more dense than inner areas. Because of the inside of a palm tree trunk's construction. That's why palm trees usually sway & bend with the wind. And rarely do they break.

Now that you've seen much of the insides of a palm tree, we think you'll realize how unique these plants are!

Takeaways for the Inside of a Palm Tree

The structure of palms are totally different from the typical woodland tree. As they're not a true tree, at all. Many have a tree-like structure, called Solitary Palms. Others are more like bushes, referred to as Clumping palms.

Whatever the growing structure they take, palms have their own way of processing all they need. And coping with the world around them.

About the Authors: Karen McGowan is the creator of MissionPalmTrees.com, and The Palm Species Navigator, along with her husband Bill. Where they share easy to read palm tree expertise gained from years of finding and studying palms in varied climates. So readers will know palms, and can avoid costly palm planting mistakes. Learn more.