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VEGETATIVE MORPHOLOGY. The Life Span of an Individual Plant. Annual – Lives for a single growing season. Biennial – Lives for two seasons, growing vegetatively during the first and flowering in the second. Perennial – Lives for three or more years and usually flowers and fruits repeatedly.
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The Life Span of an Individual Plant • Annual – Lives for a single growing season. • Biennial – Lives for two seasons, growing vegetatively during the first and flowering in the second. • Perennial – Lives for three or more years and usually flowers and fruits repeatedly.
Plant Habit • Herb • Subshrub (Suffrutescent plant) • Shrub • Tree • Succulent • Vine • Liana • Epiphyte
Roots • Usually cylindrical plant axes that lack external nodes and buds. Branch roots arise from the interior of other roots. Usually the portion of a plant that absorbs water and minerals. Most commonly, roots are underground structures, but some plants produce above-ground roots.
Types of Roots • Adventitious – From stem or leaf tissue rather than the interior of another root. • Fibrous – With all portions of the root system of more or less equal thickness, often well branched, and the primary root (taproot) absent or not obvious. • Taproot – The major root, usually enlarged and growing downward.
Other Types of Roots • Aerial – Growing above ground or water. • Fleshy – Thick with water or carbohydrate storage tissue. • Haustorial – Specialized for penetrating other plants and absorbing water and nutrients from them (as in parasites).
Stem Types • Aerial stem – Prostrate to erect above-ground stems. These are the most commonly encountered types of stems. • Rhizome – Elongated, underground horizontal stem. • Stolon – Above ground, horizontal stems called runners.
More Stem Types • Bulb – An underground stem with many fleshy scale leaves filled with stored food. • Corm – A solid underground stem in which food is stored. • Tuber – A much enlarged, short, fleshy, underground stem.
More Stem Types • Bulb – An underground stem with many fleshy scale leaves filled with stored food. • Corm – A solid underground stem in which food is stored. • Tuber – A much enlarged, short, fleshy, underground stem.
Stem Features 1/4 • Node – The position on a stem where a leaf was or is attached. • Internode – The part of a stem axis between two nodes. • Axil – The upper angle formed by a leaf and the twig to which the leaf is attached. Typically, an auxillary bud (lateral bud) forms in each leaf axil.
Stem Features 2/4 • Bud – An external meristem (either naked or protected by bud scales) found on stems. A bud may give rise to a leafy stem, a flower or a combination of vegetative and reproductive structures. • Axillary bud – A bud borne in the axil of a leaf; a lateral bud. • Terminal bud – A bud borne at the end of a stem.
Stem Features 3/4 • Bud scales – Scale leaves that cover and protect terminal and axillary buds. • Bud scale scars – The rough places or scars left on a stem when bud scales fall off. • Stipule scars – A pair of rough places or scars (or sometimes a single ring-like scar) left when stipules fall from a twig.
Stem Features 4/4 • Leaf scar – The rough place or scar left when a leaf falls from a twig. Leaf scars contain one or more dot-like scars called vascular bundle scars. The pattern of bundle scars along with the shape of the leaf scar can sometimes be used to determine the species of the plant.
More About Stems • Acaulescent – Having an inconspicuous stem. • Caulescent – Having a distinct stem. • Woody – Hard in texture, containing secondary xylem, and persisting for more than one growing season. • Twining – Spiraling around a support in order to climb.
Thorns, spines, prickles • Thorn – A reduced, sharp-pointed stem. • Spine – A reduced, sharp-pointed leaf or stipule or sharp-pointed marginal tooth. • Prickle – A sharp-pointed hair or emergence.
