Vegetative Parts of Plants Spring 2010. Descriptive Terminology LEARN DESCRIPTIVE TERMINOLOGY =...
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Transcript of Vegetative Parts of Plants Spring 2010. Descriptive Terminology LEARN DESCRIPTIVE TERMINOLOGY =...
Vegetative Parts of Plants
Spring 2010
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.
• 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
• PLANTS AND PLANT PARTS ARE NOT TO BE REMOVED
- Pesticides have been applied to all plant material.- Do not eat any plant products.
Sequoia—tallest
Sequoiadendron—most massive
Among the smallest plants in the world:Duckweeds (Lemna, Araceae)Root and 1-2 leaves; floating aquatic
Vegetative Parts of Plants
NON-REPRODUCTIVE ORGANS:
ROOTS - STEMS - LEAVES
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
Fibrous roots Tap root
Mycorrhizal associations were criticalto the invasion of land by plants andare nearly universal in plants.
endomycorrhizae ectomycorrhizae
Adventitious roots – roots produced by structures otherthan another root (e.g., stems)
Prop roots (adventitious)
Pandanus (Pandanaceae)
Root Modifications:Ficus (Moraceae) “Strangler Fig”
Adaptation for anchoring and nutrient gathering – begins as an epiphyte, and sends down adventitious roots.
Modifications of Roots: Mangroves – Anchoring, support, and aeration (coastline habitats)
Mangrove:
Pre-dehiscence germination
Root is alreadyemerged fromseed before itis separatedfrom the tree.
Root Modifications: Aerenchyma in aquatics
Haustorial roots
Found in parasiticplants.
Dodder (Cuscuta,Convolvulaceae)
StemsStems• FUNCTIONSFUNCTIONS
- support and exposure of leaves to light, flowers to - support and exposure of leaves to light, flowers to pollination agents, fruits to dispersal agentspollination agents, fruits to dispersal agents- vascular conduction of water/minerals and photosynthates- vascular conduction of water/minerals and photosynthates- sometimes the primary photosynthetic organ - sometimes the primary photosynthetic organ
• STRUCTURESTRUCTURE- nodes and internodes; rearrangement of vascular tissues- nodes and internodes; rearrangement of vascular tissues- ring of bundles or scattered bundles in primary stems- ring of bundles or scattered bundles in primary stems- secondary growth produces secondary xylem (wood)- secondary growth produces secondary xylem (wood)- epidermis in primary stems; bark in woody plants- epidermis in primary stems; bark in woody plants- buds: terminal, axillary/lateral, bud scale scars - buds: terminal, axillary/lateral, bud scale scars
• DESCRIPTIVE TERMS:DESCRIPTIVE TERMS:- Branching patterns; bulbs, herbaceous, woody- Branching patterns; bulbs, herbaceous, woody- Horizontal stems: above ground = stolons; below = - Horizontal stems: above ground = stolons; below =
rhizomesrhizomes- Vines, shrubs, trees, succulent, tendril, phylloclade, etc.- Vines, shrubs, trees, succulent, tendril, phylloclade, etc.
Fig. 4.2 from the text
Stems: Nodes and Internodes
No apparent stems!
Subterranean horizontal stems: Rhizomes
Rhizomes vs. roots
Stems: Some can be hollow;loss of pith during maturation
Modifications in the Petiolar Region
Swollen nodes: Characteristic of the PinkFamily, Caryophyllaceae
Woody Stems – Arborescent or shrubby habit
Stem Modifications:
Bark (phellem)
Most woody plants produce bark, a growth of the cork cambial layer, for mechanical protection and to reduce water loss.
Photosynthetic Stems
phylloclades
succulent stems
Basal rosette:
In plants with agraminoid (grass-like) habit, stems may not be evident.
This example is a‘tussock’ habit, forming clumps.
Bulbs: stems (internodes) are shortened and leaves are fleshy and protective.
Leaves
• FUNCTIONS- light capture, production of photosynthate,
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
Fig. 4.3 from the text
Modifications in the Petiolar Region
Sheathing leaf bases
Modifications in the Petiolar Region
Ocrea: stipular tube(characteristic of most of the Buckwheat Family, Polygonaceae)
Venation: Parallel vs. “Netted”
Unusual venation: Melastomataceae
Leaf blade:
Pinnate
Simple Compound
Palmate
Fig. 4.5 from the text
Palmate Leaf – leaflets arise from one point
Fig. 4.4 from the text
Modifications for capturing insects
Sarraceniaceae
Droseraceae
Leaf Modifications:
Kalanchoe (Crassulaceae)
Adaptation for vegetativepropagation – sheds pre-formed plantlets from leaf margins.
Fig. 4.15 from the text
Indumentum: Surface Structures Hairs, trichomes, scales
Variation in leaf shape morphology:Sassafras albidum (Lauraceae)
Armature: Thorns, spines, prickles
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, however crude, may also help.• Be sure to observe, compare and contrast
related structures to avoid interpretation errors.