Stems Botany

Epicotyle

Stem above cotyledon attachment.

Plumule

Tip of the embryo that develops into shoot

Hypocotyl

Stem below cotyledon attachment

Radicle

Tip of the embryo that develops into the root

List the three meristem tissues

1. Protoderm

2. Procambium

3. Ground Meristem

Protoderm

Gives origin to epidermis

Procambium

Produces primary xylem, primary phloem

Ground Meristem

Produces Cortex, pith

Five primary tissues

Epidermis, primary xylem, primary phloem, cortex, pith

Most monocots and dicots are

Annuals

Consists of siphonostele, Eustele, and atactostele

Herbaceous stem

Stems

Usually above ground structures of a plant that support leaves, flowers, and buds.

Herbaceous Stem

A soft stem that has not undergone secondary growth.

Woody Stem

A stem that has undergone secondary growth, producing bark and wood.

Node

Points of attachment for leaves on a stem.

Internode

Stem region between two nodes.

Axillary Bud

Bud found in the axil, the area between the base of a leaf and the stem.

Shoot Apex

The tip of the shoot containing the shoot apical meristem surrounded by developing leaves.

Epidermis

The dermal tissue that surrounds and protects the stem.

Stomata

Pores in the epidermis that allow for gas exchange.

Guard Cells

Cells that border stomata and regulate their opening.

Trichomes

Hair-like structures on the epidermal surface that help reduce transpiration.

Solenostele

A type of vascular arrangement in some eudicots where vascular tissue appears as a continuous ring.

Eustele

A vascular arrangement in most eudicots where vascular tissue is clustered into distinct bundles arranged in a ring.

Atactostele

A vascular arrangement in most monocots where vascular bundles are scattered throughout the stem.

Procambium

Cells of embryonic tissue that divide to produce primary xylem and phloem.

Fascicular Cambium

Cambium formed in the center of the vascular bundle from procambial cells.

Primary Phloem Fibers

Sclerenchyma fibers produced outside of the primary phloem.

Leaf Traces

Strands of vascular tissue that connect leaves to the stem.

Secondary Growth

Growth that results in an increase in thickness or girth of the plant.

Vascular Cambium

Secondary meristem that produces vascular tissue.

Cork Cambium

Meristem that produces phelloderm internally and cork externally.

Periderm

Dermal tissue of the secondary plant body formed from phelloderm, cork cambium, and cork.

Bark

All tissue layers external to the vascular cambium.

Inner Bark

Everything within the cork cambium.

Outer Bark

Includes the cork cambium and everything external to it.

Anomalous Secondary Growth

Growth that employs cambium that does not form a stable ring.

Lenticels

Elevated regions of the periderm that allow for gas exchange.

Branch Traces

Connect axillary shoots to the main stem.

Secondary phloem

Old layers of secondary phloem are pushed externally and crushed, except for phloem fibers.

Smooth bark

Forms when multiple periderms create perfect circles.

Rough bark

Results from multiple periderms not overlapping evenly.

Wood (Secondary Xylem)

Consists of the secondary xylem produced by the vascular cambium.

Heartwood

The oldest secondary xylem that no longer conducts water and appears darker.

Tyloses

Vessel element 'stoppers' that help block water flow in heartwood.

Tylose

Forms when a cell wall of parenchyma grows into the tracheary element.

Sapwood

Surrounds the heartwood and consists of the conducting xylem.

Tracheary Elements

Conducting cells of the xylem, either vessel elements or tracheids.

Early wood

Appears lighter and is less dense than late wood.

Annual rings

Visible in the cross section of a woody stem, used to determine the age of a tree.

Ring porous

Pattern where large vessel elements are found primarily in early wood.

Diffuse porous wood

Pattern where large vessel elements occur evenly in both early and late wood.

Hardwoods

Produced by angiosperms and contain both vessel elements and tracheids.

Softwoods

Produced by conifer trees and contain only tracheids.

Xylem rays

Tend to occupy a greater volume in hardwoods relative to softwoods.

Rhizomes

Below ground stems that burrow into the ground just below the soil surface.

Stolons

Aboveground horizontal shoots that sprout and produce new plants.

Tubers

Thick, belowground stems found at the tips of rhizomes or stolons.

Corm

A short, thick underground storage stem with thin scaly leaves.

Bulb

Stores nutrients in its fleshy leaves, differs from a corm.

Thorns

Sharp projections of plants that function in defense against herbivores.

Prickles

Form from the surface tissues of the stem rather than the whole organ.

Tendrils

Thin, string-like structures that allow the shoot to attach to other surfaces.

Cladophylls

Stems that resemble leaves in function and appearance.

Phylloclades

Flattened stems that resemble leaves and can continue growing indeterminately.

Phyllodes

Modified petioles similar to cladophylls and phylloclades.

Primary growth

Occurs at the tips of roots and shoots, causing an increase in length.

From which part of the embryo do stems originate?

Stems originate from the epicotyl area of the embryo.

The stem above the cotyledon attachment.

What is the epicotyl?

What does the plumule develop into?

The shoot.

What is the hypocotyl?

The stem below the cotyledon attachment.

What is the radicle?

The tip of the embryo that develops into the root.

What are the three primary meristems involved in stem development?

1. Protoderm, 2. Procambium, 3. Ground Meristem.

What does the protoderm give rise to?

The epidermis.

What does the procambium produce?

Primary xylem and primary phloem.

What are the five primary tissues in stems?

1. Epidermis, 2. Primary Xylem, 3. Primary Phloem, 4. Cortex, 5. Pith.

What is the function of the node in stems?

It is the attachment point of branches.

What is an internode?

The space between the nodes.

What type of stems do annuals typically have?

Herbaceous stems.

What is the structure of herbaceous dicot stems?

They have discrete vascular bundles arranged in a cylinder.

What is the role of vascular cambium in woody plants?

It produces wood and bark.

What are lenticels?

Raised areas of loosely packed cells used for gas exchange.

What are laticifers?

Latex-secreting cells originating from meristems.

What is dendrochronology?

The study of growth rings and interpreting the history of trees.

What are rhizomes?

Fleshy, creeping underground stems.

What is a corm?

A short, thickened stem usually covered with papery leaves.

What is a tuber?

An enlarged tip of a stolon that stores starch.

What are cladophylls?

Flattened, leaf-like stems.

What are thorns?

Modified stems or branches.

What is the human relevance of stems?

They provide food, sugar, medicine, spices, and materials like lumber.

What are the two types of secondary tissues in woody plants?

Bark (secondary phloem) and wood (secondary xylem).