Plant Stem Structures and Functions

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Questions and Answers

List the functions of stems, and the tissues that help the stem accomplish that function.

The function of a stem is support, conduction of water, minerals, and nutrients, production of new shoot tissue, and photosynthesis (if the stem is green). The primary tissues of the stem include the epidermis (dermal tissue system), cortex (ground tissue system, consisting of parenchyma, collenchyma, and sclerenchyma tissue), and the xylem and phloem (vascular tissue system).

Identify the origin of primary tissues in the apical meristem via the tunica-corpus. Describe the layers and function of the tunica-corpus.

Protoderm gives rise to the dermal tissue system (epidermis), procambium gives rise to the vascular tissue system (primary xylem and primary phloem), and ground meristem gives rise to the ground tissue system (parenchyma, collenchyma, and sclerenchyma). The function of the tunica-corpus is to define the surface growth (tunica) and internal tissue development (corpus) of a plant shoot. The tunica consists of the outermost cell layers that divide anticlinally, which adds surface. The corpus consists of the innermost cells that divide mostly periclinally, which adds bulk.

Explain the difference between anticlinal and periclinal cell division.

Anticlinal cell division is when cells divide perpendicular with the apical surface, whereas periclinal cell division is when cells divide parallel with the surface.

Explain the differences between Monocots and herbaceous Eudicots in regard to their internal structure of mature stems.

Eudicots have vascular bundles re-arranged in a ring around a pith region, while monocots have vascular bundles that are scattered throughout the stem and do not have a pith region. Signup and view all the answers

Compare and contrast the three basic types of stem organization including Tilia, Medicago, and Zea.

Open type with narrow interfascicular regions, which is when vascular tissue appears as a continuous cylinder with narrow interfasicular regions, as seen in Tilia. Open Type with wide interfascicular regions (pith rays), which is vascular tissue of discrete strands with wide interfascicular regions or pith rays, as seen in Medicago, Sambucus, and Ranunculus. Closed type with scattered vascular bundles, which is when vascular bundles are scattered , as seen in Zea. Signup and view all the answers

Identify the vascular connection components from stem to leaf, include the terms leaf trace and leaf gap.

Transition zone between vascular system of root and shoot: zone at or near soil level, where the vascular tissue in their roots transitions into a different stele in their stems. Roots retained initial vascular tissue but evolved to provide more structural support. Transition zone between vascular system of stem and leaf: contains leaf traces: at each node, vascular bundles that diverge from the stem and enter the base of the leaf. Also contains leaf trace gaps: the break in vascular tissue above leaf traces, and branch traces: vascular tissue that diverge from the stem and enter buds. Signup and view all the answers

Define each of the following: Node, internode, vascular bundle, fascicle, lateral bud, open type vascular bundle, closed type vascular bundle.

Node: areas of a stem where one or more leaves attach (an area, not a structure). Internode: area of a stem between nodes (an area, not a structure). Vascular bundle: a strand of conducting vessels in the stem or leaves of a plant, typically with phloem on the outside and xylem on the inside. Fascicle: bundle of vascular tissues that vascular tissues that supply food, water and minerals to a plant. Lateral (axillary) bud: a dormant apical meristem that has the potential to form a new branch (shoot). Open type vascular bundle: a vascular bundle that retains procambium, a layer of cells that separates the xylem and phloem. Closed type vascular bundle: a vascular bundle in a plant that does not retain procambium, a layer of cells that separates the xylem and phloem. Signup and view all the answers

Distinguish between the different stem modifications: rhizomes, runners, tubers, corms, thorns, and cladophylls, including examples.

Rhizome: horizontal underground stem (e.g., ginger, iris). Runner/Stolon: horizontal aboveground stem (e.g., strawberries, mint). Tuber: specialized storage stem that form at the tips of rhizomes/stolons (e.g., potatoes, cassava). Corm: underground food storage stems that are shaped like bulbs (e.g., crocus, gladiolus). Thorns: modified branches from axils of leaves (e.g., roses, blackberries). Cladophyll: modified stems that closely resemble foliage leaves (e.g., asparagus, butcher's broom). Signup and view all the answers

What is the function of a rhizome?

To store food (like starches and proteins) for a plant. Signup and view all the answers

What is the function of a runner/stolon?

A means of asexual reproduction by producing new plants at nodes along its length, allowing a plant to spread rapidly and colonize new areas. Signup and view all the answers

What is the function of a tuber?

As a plant's storage organ, holding nutrients to help the plant survive through harsh conditions like winter or drought, providing energy for new growth when needed, and sometimes acting as a means of asexual reproduction. Signup and view all the answers

What is the function of a storage stem?

A reservoir to store food (like carbohydrates) and water for a plant. Signup and view all the answers

What is the function of thorns?

Protect plants from being eaten by herbivores. Signup and view all the answers

What is the function of cladophylls?

Carry out photosynthesis in plants where true leaves are reduced or absent. Signup and view all the answers

Which of the following is an example of a rhizome?

Ginger (D) Signup and view all the answers

Which of the following is an example of a runner/stolon?

Strawberries (B) Signup and view all the answers

Which of the following is an example of a tuber?

Potatoes (C) Signup and view all the answers

Which of the following is an example of a cladophyll?

Asparagus (B) Signup and view all the answers

Distinguish between the different stem modifications: rhizomes, runners, tubers, corms, thorns, and cladophylls.

Rhizome: horizontal underground stem. Runner/Stolon: horizontal aboveground stem. Tuber: specialized storage stem that form at the tips of rhizomes/stolons. Corm: underground food storage stems that are shaped like bulbs. Storage stems. Thorns: modified branches from axils of leaves. Cladophyll: modified stems that closely resemble foliage leaves. Function of a rhizome: to store food (like starches and proteins) for a plant. Function of a runner/stolon: a means of asexual reproduction by producing new plants at nodes along its length, allowing a plant to spread rapidly and colonize new areas. Function of a tuber: as a plant's storage organ, holding nutrients to help the plant survive through harsh conditions like winter or drought, providing energy for new growth when needed, and sometimes acting as a means of asexual reproduction. Function of a corm: an underground storage organ for plants, storing starches and nutrients to enable the plant to survive unfavorable conditions like winter or drought, and to fuel its growth when conditions improve. Function of a storage stem: a reservoir to store food (like carbohydrates) and water for a plant. Function of thorns: protect plants from being eaten by herbivores. Function of cladophylls: carry out photosynthesis in plants where true leaves are reduced or absent. Examples of rhizomes: ginger, iris, bamboo, turmeric, lily of the valley, poison oak, rhubarb, snake plant, banana, ferns, and sugarcane. Examples of runners/stolons: strawberries, mint, spider plants (Chlorophytum comosum), bermudagrass, creeping buttercup (Ranunculus repens), silverweed (Argentina anserina), Ajuga (bugleweed), and creeping charlie (Glechoma hederacea). Examples of tubers: potatoes, cassava, and dahlias. Signup and view all the answers

Give examples of corms, storage stems, thorns and cladophylls.

Examples of corms: crocus, gladiolus, freesia, cyclamen, taro (colocasia), saffron crocus, water chestnut, and tuberous begonias. Examples of storage stems: potatoes (tubers), ginger (rhizomes), onions (bulbs), garlic (bulbs), crocus (corms), iris (rhizomes), and yams (corms). Examples of thorns: examples: roses, blackberries, cacti, barberry, bougainvillea, and hawthorns. Examples of cladophylls: examples: asparagus (where the "needle-like" foliage are actually modified stems called cladodes), butcher's broom (Ruscus aculeatus) which has flattened, leaf-like cladodes, and some species of Euphorbia which often have thick, succulent stems acting as cladophylls. Signup and view all the answers

Flashcards

Functions of stems

Support, conduction of water, minerals, and nutrients, production of new shoot tissue, and photosynthesis (if stem is green)

Primary tissues origin

Protoderm: epidermis. Procambium: primary xylem and phloem. Ground meristem: parenchyma, collenchyma, and sclerenchyma.

Anticlinal vs. Periclinal division

Anticlinal divides perpendicular to the surface. Periclinal divides parallel with the surface.

Monocot vs. Eudicot stems

Eudicots: vascular bundles in a ring around a pith. Monocots: vascular bundles scattered without a pith.