Download Systematic Implications of DNA variation in subfamily

Vegetative Parts of Plants
Spring
2012
Descriptive Terminology
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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 Conservatory
5th floor – Bessey Hall
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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
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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
storage
buttress
Fig. 9.2 from Simpson
pneumatophores
Fibrous roots
Tap root
Adventitious roots – roots
produced by structures other
than another root (e.g., stems)
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 parasitic
plants.
Host stem
Dodder (Cuscuta,
Convolvulaceae)
Buttress roots
Modifications of Roots:
Mangroves – Anchoring, support, and
aeration (coastline habitats)
Mangrove:
Pre-dehiscence
germination
Root is already
emerged from
seed before it
is separated
from the tree.
Root Modifications: Aerenchyma in aquatics
Mycorrhizal associations were critical
to the invasion of land by plants and
are nearly universal in plants.
endomycorrhizae
ectomycorrhizae
Stems
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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 Pink
Family (Caryophyllaceae)
Vines and climbers:
Photosynthetic Stems
cladodes
succulent stems
Tussock:
In plants with a
graminoid (grasslike) 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):
wsu.edu
energyfarms.com
Bulbs: stems (internodes) are
shortened and leaves are fleshy
and protective.
Woody Stems – Arborescent or
shrubby habit
Stem Modifications:
Bark (phellem or cork)
Most woody plants
produce bark, a growth of
the cork cambial layer, for
mechanical protection and
to reduce water loss.
Leaves
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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)
Modifications in
the Petiolar Region
Sheathing leaf bases
Venation: Parallel vs. “Netted”
Unusual venation: Melastomataceae
Leaf blade:
Simple
Compound
Pinnate
Palmate
Compound
leaves
Fig. 9.9,
Simpson
Palmate Leaf – leaflets arise from one point
Leaf Arrangement
Variation in leaf shape morphology:
Sassafras albidum (Lauraceae)
Leaf modifications: bracts
Leaf modifications
Leaf tendrils
Bud scales
Modifications for capturing insects
Droseraceae
Sarraceniaceae
Leaf Modifications:
Kalanchoe (Crassulaceae)
Adaptation for vegetative
propagation – sheds preformed plantlets from leaf
margins.
Bulbs: stems (internodes) are
shortened and leaves are fleshy
and protective.
Indumentum: Surface Structures
Hairs, trichomes, scales
Hair types
Fig. 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
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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.