Dicotyledon Stem Model

Quick Answer: The Dicotyledon Stem Model is an enlarged dicot stem model showing the internal tissues of the young stem of a flowering plant with two seed leaves, such as a sunflower: epidermis, cortex, a ring of vascular bundles and a central pith. It is used in botany lessons on stem anatomy and on the difference between dicots and monocots.

Tissues of a Young Dicot Stem

Dicot stem models are normally built around a transverse section, often as a three-dimensional block so the tissues can be followed a short way along the stem. The listing does not state which form this model takes, which plant it is based on or its size, so confirm these points; the anatomy below is what a dicot stem section is used to teach.

From the outside inward, the epidermis carries a waxy cuticle and often multicellular hairs. Under it lies the hypodermis of collenchyma, whose thickened cell corners give flexible support, then a cortex of loosely packed parenchyma ending in a starch-rich endodermis, sometimes called the starch sheath. Inside that is the pericycle, often with patches of sclerenchyma capping each vascular bundle. The bundles form a single ring; each is conjoint and collateral, with phloem outside and xylem inside, and open, because a strip of cambium lies between the two. Between the bundles, medullary rays of parenchyma connect the cortex to the large central pith.

The cambium is what separates dicot and monocot stems in function as well as appearance. In a dicot it joins up into a complete ring and adds secondary xylem and phloem each season, producing wood and the annual rings of trees. Monocot stems have scattered, closed bundles without cambium, as the T.S. monocot stem model shows, and do not thicken in the same way. The dicot stem structure chart is a matching wall reference.

Specifications

Botany Lessons

• Identifying stem tissues before examining stained sections under the microscope
• Comparing dicot and monocot stems in practical examinations
• Introducing secondary growth, wood formation and annual rings
• Explaining the transport roles of xylem and phloem

Care & Handling

• Stand the dicot stem model on its base or a flat surface; the raised tissue layers on the cut face chip if it is laid face down.
• Wipe with a slightly damp cloth, without solvents, so the colour coding of the tissues stays clear.
• Keep it in a closed cupboard between practicals to limit dust in the textured surfaces.

Why Choose LabEquip

Botany teachers at school and college level buy a dicot stem model so students can find each tissue in three dimensions before tackling a thin microscope section. LabEquip lists it among its biology lab products; for form and size, write via the contact page.

Frequently Asked Questions

How can a dicot stem be told apart from a monocot stem?

A dicot stem has vascular bundles arranged in a ring, each with cambium between xylem and phloem, and a clear pith. A monocot stem has many bundles scattered through ground tissue, with no cambium and no distinct cortex and pith.

What does open vascular bundle mean?

In an open bundle a thin strip of cambium separates the xylem from the phloem. Because cambium cells keep dividing, they can add new vascular tissue and let the stem thicken. Closed bundles, as in monocots, lack this strip.

What is the function of collenchyma in the stem?

Collenchyma cells have walls thickened at the corners, which gives the young stem strength while letting it bend and keep growing. It usually forms a layer just under the epidermis.

What is the starch sheath?

It is the endodermis of a dicot stem, the innermost layer of the cortex. Its cells are rich in starch grains, which turn blue-black with iodine, and that is how the layer got its name.

Where is xylem found in a dicot stem vascular bundle?

On the inner side, towards the pith, with phloem on the outer side towards the cortex. The first-formed xylem lies closest to the centre, an arrangement called endarch.

How does a dicot stem develop wood?

The cambium in the bundles links up with new cambium between them to form a complete ring. This ring adds secondary xylem inward and secondary phloem outward each growing season, and the build-up of secondary xylem is wood.

Last Updated: September 2026