Plant Form and Function Flashcards
Roots
the plant part not having leaves or nodes
Tap Root System
long central shaft to store nutrients and to reach deeper water tables
Fibrous/Diffuse Root System
primary function is to support plant, secondary function is to access more shallow water supply
Tuber
sweet potato; swollen energy-storing roots
Adventitious (prop) root systems
root emerges from stem just above ground to help support plants in shallow soils
seen in the tropics
snorkel roots
pneumatophores
emerge below ground but rise above ground to obtain oxygen fo respiration within the root. Usually present in species that have roots in water-saturated soil or standing in water.
Roots general functions
- provides moisture and inorganic ingredients to plant
- attaches plant to ground to let them reach for radiant energy above ground or to climb/attach to verticle surfaces for the same purpose (as seen in Ivy)
- Long term starch storage (ex carrots and potatos)
- Access oxygen (ex pheumatophores on mangroves)
stems/trunks/shoot
axial
central column w/ spire shape for strength and shedding snow (spruce)
palm trunks are bare to reduce the lateral wind pressure in tropical storms
Dendritic
Sub-branching for greater photorespiration
Buttressed Trunk
for greater support in thin tropical soils
Stems/Trunks/Shoot Functions
- Transport Nutrients/Water between leaves and roots
- Access to available light above surrounding structures
- Asexual reproduction- lateral stem runners above ground (stolons) and below ground (rhizomes)
- Photosynthesis in arid-dwelling plants, ex. cactus
- Water storage- cactus and certain vines
- Protection-thorns are modified stems
- Food storage- Underground stems: white potato, yams
Types of Leaves
simple, compound, doubly compounded, and needles
needles function
give maximum water conservation and reduced (but year round) photosynthesis
Leaves Functions
- Photosynthesis- large doubly compounded leaves like ferns w many spaces to avoid rain damage
- Water collectors w leaves angled down toward central stem and axil collection basil
- attachment to other vegetation for climbing- pea leaf tendrils
- defense- most cactus spines are modified leaves
- water storage- aloe vera, succulent plants
- Obtaining supplementary nitrogen- carnivorous plants
secondary cell wall
specialized chemical components corresponding w the cells specialized function
ex. waxy substances for the cuticle; lignin in xylem tissue for strength
Meristematic Cells
-Undifferentiated
-Rapidly dividing
-Simple primary cell wall that comprise the layers of active plant growth; are thin and flexible to enable the daughter cells to elongate
one daughter cell remains undifferentiated and rapidly dividing, the other usually becomes slightly “differentiated”-mainly in being less mitotically active and more ready to produce functionally differentiated cells
Areas of active plant growth
-apical (stem and root tips
-lateral meristems (cambium)
cambium is a tissue layer that produces layers of xylem and phloem in woody plants and encourages the growth of roots and stems
Parenchyma cells
-primary cell wall only; thin and flexible
-can either revert back to meristematic tissue, or form dermal tissue, ground tissue (leaf mesophyll cells, root cortex cells), and repair tissue
-less actively dividing than meri. cells
-remain alive
-make up the phloem cells
most common mature cells in the plant, close desc. of meristematic cells
dermal tissue
outer, single cell layer giving rise to root hairs, trichomes, leaf guard cells, and waxy cuticle
totipotent cell
a cell can be considered totipotent if it able to autonomously develop into a whole plant via embryogenesis
companion cell
large elongated cells of phloem that maintain the pressure gradient in the sieve tube elements
found only in angiosperms, a type of parenchyma cell
sieve-tube cells
are almost always ajacent to companion cells, formed from a series of elongated cells; the conducting element of phloem
Collenchyma cells
-Longer, thicker primary cell walls w somewhat more cellulose (no secondary wall)
-Function primarily in support (ex in vascular bundles)
-Can still stretch and elongate (ex in elongation zones near apical meristems)
much less abundant in the plant
seen in celeray stalks and most vascular bundles
Collenchyma cells
-Longer, thicker primary cell walls w somewhat more cellulose (no secondary wall)
-Function primarily in support (ex in vascular bundles)
-Can still stretch and elongate (ex in elongation zones near apical meristems)
much less abundant in the plant
seen in celery stalks and most vascular bundles
Sclerenchya cells
-secondary cell wall impregnated w lignin
-do not permit stretching and elongation
-found in non-growth areas of the tree
-lose their cytoplasm and die when mature, leaving just the cell wall material
make up the xylem
make up tracheid cells, vessel elements, elongated fibers, and sclerid cells
Tracheid cells
pitted tracheid cells retain a thin primary cell wall at the pits
the only cell type in xylem of many nonflowering plants
longer, thinner, and ends taper in comparison to vessel elements
vessel elements
larger than tracheid cells and have large terminal openings devoid of all tissue
schlerenchyma cell
elongated fibers
purely supportive tissue for making rope, hemp, and linen
schlerenchyma cell
sclereid cells
short and tough schlerenchyma cells that reinforce nut shells and seed coats
What is in the…
Epidermis
(of plants)
waxy cuticle, trichomes, stomata
-majority of stomata are on underside of the leaf closer to the spongy mesophyll, however
waxy cuticle function
reduces water loss, protects against pathogens, and protects against herbivores
Trichomes
the trichomes thwart small herbivorous insects, reflect exess incoming solar radiation, and conserve water
Stomata function
guard cells and pores
-The kidney bean shaped guard cells take in water and become turgid (rigid) when moisture is present, opening a pore between them.
-Guard cells become flaccid and close the pore during dry conditions
-Stomata regulate water vapor (transpiration) and gas passage in and out of the leaf
Palisade mesophyll
elongated parenchyma cells, site of most photosynthesis
Spongy mesophyll
space for gas and water exchange
Vascular bundle in mesophyll
xylem, phloem, and supportive collencyme cells
Cross Section of a Leaf Order
-cuticle
-upper epidermis
-palisade mesophyll
-spongy mesophyll
-lower epidermis
-cuticle
Stem/Trunk Cross section of dicotyledon order
from bark inward
- Bark
- Cork cambium
- Secondary Phloem Cells
- Secondary Vascular Cambium
- Secondary Xylem Cells
- Sapwood
- Heartwood
Bark
cork cells
Cork Cambium
produces cork cells, often with lignin, to outside the cork cambium layer
in between bark and secondary phloem cells
Secondary Phloem Cells
transport photosynthate, nutrients
in between cork cambium and secondary vascular cambium
Secondary vascular cambium
-Produces secondary phloem cells to the outside
-Produces secondary xylem cells to the inside
-Produces parenchyma cells horizontally (rays) that transport fluids/nutrients between inner and outer cells of the trunk
in between secondary phloem cells and secondary xylem cells
Secondary Xylem Cells
tree
are active in water transport
in between secondary vascular cambium and sapwood
sapwood
tree
light colored xylem layer active in water transport
in between secondary xylem cells and heartwood
heartwood
tree
dark colored xylem in core of a tree that no longer transports water, but serves as a depot for resin (anti-microbial and anti-fungal properties)
Root cross section order
from surface inward
- epidermis (with lateral roots and root hairs)
- Cortex
- Vascular Cylinder-
3a. Endodermis
3b. Pericycle
3c. Phloem
3d. Xylem
Root
Epidermis
roots
-waxy cuticle layer reduced, increased root surface area for water/nutrient absorption
contains lateral roots and root hairs
Cortex
roots
Parenchyma food-storage cells in the ground tissue of the root
Vascular Cylinder
roots
in center, or if multiple, dispersed vascular bundles in cortex
includes endodermis, pericycle, and primary xylem + phloem
Endodermis
root
important barrier in plant root functioning, site of Casparian strip
Pericycle
layer from with lateral roots begin and grow
root system
Primary Growth Zones
caused by apical meristems- increases the length of root and shoots
- Cellular Division Zone- A. Root Cap (loose epidermal cells); mucigel lubricant secreted to facilitate growth through soil. B. Apical meristem (tiny area of undifferentiated, but actively dividing tissue. C. Primary Meristem (just above apical meristem in root)- cells begin to differentiate
- Elongation Zone
- Absorption Zone
shoot system is similar to root tip but with leaves and lateral buds instead of root hairs
Secondary Growth Zone
caused by lateral meristems (cambium)
results in increased girth (diameter) of the plant
Lateral meristem- cylinder of actively dividing tissue running the length of the plant and occuring just inside the perimeter of the stem or trunk
Two types of lateral meristems
Cork cambium (located outside the secondary phloem cells) and vascular cambium (located inside the cork cambium layer)
Cork Cambium
produces cork cells (bark) only to the outside of the cork cambium layer; no tissue layer is generated to the inside
located outside the secondary phloem cells
Vascular cambium
located inside the cork cambium layer
A. produces phloem cells to the outisde of the cambium layer; this layer doesn’t increase in width much because as new phloem cells are added, older phloem cells disintegrate and are reabsorbed near the cork cambium
B. Produces Xylem cells inside the vascular cambium next to previous xylem tissue, and bc old xylem tissue doesn’t disintegrate, the girth of the tree increases
-several cell layers occur each growing season; spring cells are larger than late summer cells
-entire seasonal record is one growth ring
-no tisue layer generated to the inside; located in cork camb. layer
Reproductive Zones
Flowers, seeds, and fruits
The flower (general overview)
-primary design+function is to arrtact pollinating insects, bats, birds+small mammals by visual and/or chemical info (sometimes just one species, tailored by the pollinator
-protects gametes
-Provides forsexual reproduction
-promotes seed dispersal through fruit formation (a reward for the seed dispersing animal)
flowers facing down near ground for small mammals, figh and facing upwards for insects and birds
Sepals
- thicker, leaf-like photosynthesizing structures
- enclose the developing flower bud and other reproductive structures
- protects them from insects and disease
petals
- generally thinner, leafy, colorful and scented structures
- located in a whorl inside the sepals
- serves to attract pollinators
nectary at petal base may occur (contains a reward for pollinators)
-entire pedal assemblage is termed the corona
stamen
- structure producing the male gametophyte (pollen)
- composed of filament (support shaft) and a terminal pad of pollen (anther)
Carpel
- reproductive structure that produces female gametophytes (and eventually eggs)
- each composed of a swollen basel ovary with ova, a tubular style, and a terminal stigma upon which pollen lands and initiates growth of the pollen tube conveying the male gametes to the ova for fertilization
Seed
-consists of a plant embryo, an endosperm as a nutrient source, and a seed coat
-seed has a longer lifetime and is less vulnerable to environmental extremes than a eukaryote spore
