Lab 15 Review: Vegetative organs

• roots are anchorage and absorption

• stems support leaves, flowers, and fruit

• leaves carry out photosynthesis

Roots

1. Storage roots

Biennial plants: 2 years- (living two growth seasons)

1st year, food is made by photosynthesis is stored in the roots as starch

In their 2nd year energy stored is used to produce flowers/fruit which then make seeds

Function: food storage

Examples: carrots, turnips, beets, sweet potato

2. Pneumatophores (snorkel roots)

• Found in trees anchored in water-saturated in soil (along shorelines of streams, lakes, bays)

• vertical stems arising from the tree’s roots which allow the living cells of the roots to take in oxygen and release CO₂

• They are sometimes called knees

Function: gas exchange

Examples: bald cypress, mangrove

3. Adventitious roots - climbing roots

• roots that arise from stem

• roots secrete(produces) an adhesive that firmly anchors a vine to an upright structure

• grow vertically towards light

Function: attachment/support

Example: poison ivy, Virginia creeper

4. Adventitious roots - prop roots

• found in stalk-like plants with shallow root systems

• emerge just above the ground and grow down to the soil, providing much needed support of the upright stem

• live in water-saturated: (completely wet or full of moisture) that does not provide enough support to anchor the tree

• prop roots literally prop

Function: support

Examples: corn, sugar cane, mangrove tree

Stems

1. Stolons - (runners)

• Horizontal ←-→

• aboveground stems

• new plants arise from the nodes of stolons

• asexual reproduction

Function: vegetative propagation

Examples: crab grass, St. Augustine grass, strawberry plant

2. Rhizomes

• Horizontal

• underground stems

• new plants emerge from them

• asexual reproduction

Function: vegetative propagation

Examples: ginger “root”, irises, cattails

2. Thorns

They are botanically: (something involves or relates to plants)

• modified leaves or prickles

• outgrowths of bark or epidermis of a stem

Function: protect from herbivores

Examples: honey locust, crabapple tree, ocotillo, rose plants

3. Tubers

• deposits starch in internodes of underground stems

• stem swells and nodes remain visible as “eyes”

• each eye includes a bud

Function: starch storage

Examples: white potato, red potato

4. Corms

• enlarged underground stem covered by a thin layer of papery leaves

• produce flowers by sexual reproduction when they emerge from soil

• food made by photosynthesis and stored in underground corm

• leaves die but corm remains for new growth

Function: food storage

Examples: gladiola, crocus

5. Cladophylls

• flattened photosynthetic stems that have a leaf-like appearance

some plants use cladophylls as an adaption for arid: (dry or no rain) habitats

• stem takes over the function of photosynthesis while leaves are greatly reduced in size, completely lost or modified into spines

• reduced in leaf size equates to water stomata through which water would be lost

Function: water conservation/storage, photosynthesis

Example: prickly pear cactus, Christmas cactus

Leaves

1. Spines

spines are modified to protect cladophylls and other photosynthetic succulents stems from animals seeking water they contain

• cactus are over 95% water

• spines have much less surface area than typical leaves

• no stomata

Function: protection

Examples: cacti

2. Bulbs

• very small stem with tiny roots

• rest of bulb consist of fleshy leaves that store carbohydrates made by photosynthesis

• energy stored is used to promote flowering like corms

Function: food storage

Examples: tulip, onion, garlic

3. Succulent leaves

• arid land plants

• thick with lathery covering and sunken stomata

• leaves are very reduced

• stem is fleshy and photosynthetic

Function: water conservation

Examples: jade plant, aloe vera

4. Reproductive leaves

Tiny plantlets are produced along the edges of leaves

• these fall off and start new plants

Function: vegetative propagation

Examples: African violet, Kalanchoe

5. Tendrils

curl around other plants and upright structures

• allows plants with tendrils to climb towards sunlight

• support weak branches

*Some tendrils are modified stems instead of leaves*

• leaf tendrils extend from the ends of compound leaves

• stem tendrils arise from the axil of the leaf - the angle between the stem and the leaf

Function: attachment and support

Examples: vetch, garden peas

6. Insectivorous traps

leaves modified for capturing and digesting insects

• found in habitats with frequent rainfall that leeches soil nutrients

• insects are not used for source of energy but for nitrogen

• soil lacks in nitrogen

• they use photosynthesis

Function: acquire nitrogen

Examples: pitcher plant, Venus's flytrap, sundew

7. Bracts

colored leaves that replace or enhance the function of flower petals

Function: attraction of pollinators