Vegetative Terminology (Part 3)

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Economic Plant Illustrations #30

Botany 115 Vegetative Terminology

Modified Roots, Stems and Leaves (Part 3)

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Phyllodes & Cladodes: Modified Leaves & Stems

Left: Ribbonbush or tapeworm plant (Homocladium platycladum), an unusual member of the buckwheat family (Polygonaceae) native to the Solomon Islands. The flattened, leaflike stems arise from the axils of true leaves. Right: Sydney golden wattle (Acacia longifolia), an Australian shrub commonly grown in southern California. The leaves are technically flattened petioles called phyllodes. On some acacias, true bipinnate leaves sometimes develop from the tips of the phyllodes.

Phyllodes of (A) black acacia (Acacia melanoxylon) compared with (B) Sydney golden wattle (A. longifolia). The black acacia phyllodes have pinnate leaves at their tips, showing that they are modified petioles.

Acacias With Modified Petioles Called Phyllodes
See The Wayne's Word Article About Acacias

In the above photos, each minute, scalelike leaf (red arrow) has a flattened, leaflike branchlet called a cladode or cladophyll in its axil. These cladophylls function like leaves, but they are really modified stems. Left: Butcher's broom (Ruscus aculeatus), a dioecious, low-growing evergreen shrub native to the Azores, western Europe, through the Mediterranean region to Iran. Right: Dried herbarium specimen of smilax asparagus (Asparagus asparagoides), a South African branching vine related to the garden asparagus (A. officinalis). Both of these unusual cladode-bearing plants belong to the lily family (Liliaceae).

Fascicled storage roots and cladodes of smilax asparagus (Asparagus asparagoides). Although cultivated as an ornamental, this plant may become an invasive weed in well-watered soils of southern California. It is called smilax asparagus because it belongs to the same genus as the garden asparagus, and its leaves superficially resemble those of Smilax species.

See Garden Asparagus: An Edible Stem Vegetable

Tendril: Modified Coiled Stem That Twines Around A Support

Typical tendrils of the gourd family (Cucurbitaceae), including pumpkins and squash. Note: The tendrils of some climbing plants are modified leaves, such as the coiled leaf rachises of sweet pea (Lathyrus odoratus).

The scarlet trumpet vine (Distictis buccinatoria) is commonly cultivated in southern California. The tendrils have circular pads that adhere to the stucco walls of buildings. This beautiful vine from tropical Mexico belongs to the bignonia family (Bignoniaceae).

Compound leaf of the scarlet trumpet vine (Distictis buccinatoria), a tropical Mexican vine with climbing tendrils. Since the tendrils develop from rachises of compound leaves, they are modified leaves rather than adventitious roots. On concrete walls the tendrils develop circular pads on the tips that bond to the stucco.

Scarlet trumpet vine (Distictis buccinatoria), a tropical Mexican vine with climbing tendrils. On concrete walls the tendrils develop circular pads on the tips that bond to the stucco. Since the tendrils develop from rachises of compound leaves, they are modified leaves rather than adventitious roots. This beautiful vine belongs to the bignonia family (Bignoniaceae).

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