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Descriptive Terminology
• LEARN DESCRIPTIVE TERMINOLOGY = PHYTOGRAPHY
- Vegetative- Floral/inflorescence- Fruit
• ASSOCIATE STRUCTURES WITH TERMS- Significant range of variation- Learn to identify major structures and
modifications
R. W. Pohl Conservatory5th floor – Bessey Hall
• AVAILABLE TO BIOLOGY 366 STUDENTS - Free to look at plants to get a better idea of morphological structures and taxonomic diversity.
• OPEN HOURS ARE 9:00 a.m. to 5:00 p.m. Monday - Friday- Some Friday afternoons conservatory is closed for
pesticide applications. Some research areas are not available for general viewing.
- Access by the elevator.
• PLANTS AND PLANT PARTS ARE NOT TO BE REMOVED- Pesticides have been applied to all plant material.- Do not eat any plant products.- Do not disturb any research areas.
Among the smallest plants in the world:Duckweeds (Lemna, Araceae)Root and 1-2 leaves; floating aquatic
Roots• FUNCTIONS
- Anchoring and support- Absorption of water and mineral nutrients; mycorrhizae
• STRUCTURE- xylem and phloem usually in a central
vascular strand- no cuticle (except on aerial roots), root hairs.- branching pattern variable; adventitious roots- no nodes/internodes present in roots!
• DESCRIPTIVE TERMS:- Taproot (carrot) vs. fibrous roots (grass)- Fibrous, adventitious, aerial, fleshy, prop
Mycorrhizal associations were criticalto the invasion of land by plants andare nearly universal in plants.
endomycorrhizae ectomycorrhizae
Root Modifications:Ficus (Moraceae) “Strangler Fig”
Adaptation for anchoring and nutrient gathering – begins as an epiphyte, and sends down adventitious roots.
Mangrove:
Pre-dehiscence germination
Root is alreadyemerged fromseed before itis separatedfrom the tree.
Stems• FUNCTIONS
- support and exposure of leaves to light, flowers to pollination agents, fruits to dispersal agents- vascular conduction of water/minerals and photosynthates- sometimes the primary photosynthetic organ
• STRUCTURE- nodes and internodes; rearrangement of vascular tissues- ring of bundles or scattered bundles in primary stems- secondary growth produces secondary xylem (wood)- epidermis in primary stems; bark in woody plants- buds: terminal, axillary/lateral, bud scale scars
• DESCRIPTIVE TERMS:- Branching patterns; bulbs, herbaceous, woody- Horizontal stems: above ground = stolons; below =
rhizomes- Vines, shrubs, trees, succulent, tendril, phylloclade, etc.
Modifications in the Petiolar Region
Swollen nodes: Characteristic of the PinkFamily, Caryophyllaceae
Stem Modifications:
Bark (phellem)
Most woody plants produce bark, a growth of the cork cambial layer, for mechanical protection and to reduce water loss.
Tussock:
In plants with agraminoid (grass-like) habit, stems may not be evident.
This example is a‘tussock’ habit, forming clumps.
Leaves
• FUNCTIONS- light capture, production of photosynthates,
transpiration
• STRUCTURE- petiole, stipules, pulvinus, blade (lamina), veins- vestiture (minimally a cuticle), hairs, scales, etc.- simple vs. compound (blade divided into discrete parts)- many modifications, including extreme reduction- virtually always with a bud or branch in the axil
• DESCRIPTIVE TERMS:- Many, based on leaf shape, size, color, venation,
margin, apex, base, arrangement, number, presentation
Modifications in the Petiolar Region
Ocrea: stipular tube(characteristic of most of the Buckwheat Family, Polygonaceae)
Leaf Modifications:
Kalanchoe (Crassulaceae)
Adaptation for vegetativepropagation – sheds pre-formed plantlets from leaf margins.
Summary• Vegetative structures important in
describing plants.• Variations on similar basic morphology can
be diagnostic for certain plant groups.• An understanding of descriptive terms is
essential for plant identification and to understand morphological evolution.• Make lists of terms and their associated
structures; drawings or diagrams, however crude, may also help, as will photos.• Be sure to observe, compare and contrast
related structures to avoid interpretation errors.