Download - Vegetative Parts of Plants
Vegetative Parts of Plants
Spring 2013
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. Pay attention to warning signs!
• 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.
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
Fig. 9.1 from Simpson
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- no nodes/internodes present in roots!
• DESCRIPTIVE TERMS:- Taproot (carrot) vs. fibrous roots (grass)- Fibrous, adventitious, aerial, fleshy, prop- Adventitious roots (from stems)
Fibrous roots Tap root
Adventitious roots – roots produced by structures otherthan another root (e.g., stems)
storage buttress pneumatophores
Fig. 9.2 from Simpson
Root modifications
Root Modifications:Ficus (Moraceae) “Strangler Fig”
Adaptation for anchoring and nutrient gathering – begins as an epiphyte, and sends down adventitious roots.
Prop roots (adventitious)
Pandanus (Pandanaceae)
Haustorial roots
Found in parasiticplants.
Host stem
Dodder (Cuscuta,Convolvulaceae)
Buttress 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
Mycorrhizal associations were criticalto the invasion of land by plants andare nearly universal in plants.
endomycorrhizae ectomycorrhizae
Roots and other organisms
Some angiosperm families(primarily the legumes, Fabaceae) have root nodules housing nitrogren-fixing bacteria
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, cladode, etc.
Fig. 9.1 from Simpson
Stems: Nodes and Internodes
Fig. 9.3 from Simpson
Herbaceous stems:
Stems: Some can be hollow;loss of pith during maturation
Modifications in the Petiolar Region
Swollen nodes: Characteristic of the PinkFamily (Caryophyllaceae)
Vines and climbers:
Photosynthetic Stems
cladodes
succulent stems
Tussock:
In plants with agraminoid (grass-like) habit, stems may not be evident.
This example is a‘tussock’ habit, forming clumps.
Basal rosette:
No apparent stems!
Subterranean horizontal stems: Rhizomes
Rhizomes vs. roots
Tubers (underground storage stems):
energyfarms.com
wsu.edu
Bulbs: stems (internodes) are shortened and leaves are fleshy and protective.
Woody Stems – Arborescent or shrubby habit
Stem Modifications:
Bark (phellem or cork +2° phloem)
Most woody plants produce bark, a growth of the cork cambial layer, for mechanical protection and to reduce water loss.
lenticels
Bark variation
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
Basic leaf structure
Stipules
Modifications in the Petiolar Region
Ocrea: stipular tube(characteristic of most of the Buckwheat Family, Polygonaceae)
pulvinus(lower)axillary bud
Modifications in the Petiolar Region
Sheathing leaf bases
Venation: Parallel vs. “Netted”
Unusual venation: Melastomataceae
Leaf blade:
Pinnate
Simple Compound
Palmate
Compound leaves
Fig. 9.9,Simpson
Palmate Leaf – leaflets arise from one point
Twice-pinnately compound
Leaf Arrangement
Variation in leaf shape morphology:Sassafras albidum (Lauraceae)
Leaf modifications: bracts
Leaf modifications
Leaf tendrils
Bud scales
Modifications for capturing insects
Sarraceniaceae
Droseraceae
Leaf Modifications:
Kalanchoe (Crassulaceae)
Adaptation for vegetativepropagation – sheds pre-formed plantlets from leaf margins.
Bulbs: stems (internodes) are shortened and leaves are fleshy and protective.
Indument(um): Surface Structures Hairs, trichomes, scales
Hair typesFig. 9.59 in Simpson
Armature: Thorns, spines, prickles
And the ultimate leaf modifications:
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.