Lesson 4: Roots and Stems

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Types of Root

Taproot, Fibrous, Adventitous

Root Cap

• A covering of cells over the root tip that protects delicate apical meristematic tissue directly behind it

• Thimble-like layer

• Each tip has a root cap

Root Hair

• Increases root surface area, which also increases absorptive capacity.

Prop Roots

• Adventitious root that arises from the stem and provides additional support for the plant

• Grows upwards

Examples of Prop Roots

• Banyan Tree, Hala Tree, Mangrove

Buttress Roots

• Holds tree upright and aids in extensive distribution of shallow roots 

• Roots above/on surface of the ground

Examples of Buttress Roots

•  Jackfruit, Dao

Pneumatophore

• Specialized aerial root that grows in swampy areas

• May facilitate gas exchange between atmosphere and submerged roots

Examples of Pneumatophore

• White and Black Mangroves

Types of Stem

Woody and Herbaceous

Bud

• underdeveloped shoot that contains an embryonic meristem

Terminal Bud

end of stem

Auxiliary Bud

side of stem

Node

the area on the stem where one or more leaves are attached.

Internode

space in between nodes

Cortex

• Complex tissue

• Contains parenchyma, collenchyma, and sclerenchyma cells.

Parenchyma

• Stores starch and crystals

Collenchyma / Sclerenchyma

• Confer strength and support for the system

Xylem

Transports water and dissolved minerals from the roots to the leaves.

Phloem

Transported dissolved carbohydrates from the leaves to the roots.

Vascular Cambium 

• In between xylem and phloem

• Responsible for secondary growth

Pith

A ground tissue composed of large, thin-walled parenchyma cells functioning as storage.

Rhizome

• Horizontal underground stem that often serves as a storage organs and a means of se//xual reproduction.

Examples of Rhizomes

bamboos, ginger, turmeric

Tuber

• Thickened end of a rhizome that is fleshy and enlarged for a food storage.

Examples of Tubers

potatoes, yam, sweet potatoes, cassava

Bulb

• Rounded, fleshy underground bud that consists of short stem fleshy leaves

Examples of Bulbs

onion

Corm

• Short, thickened underground stem specialized for food storage and asexual reproduction

Examples of Corm

Taro

Stolons

An aerial horizontal with long internodes, forming buds that develop into separate plants

Examples of Stolons

Strawberry