Transcript Psilotum

Psilotum
This seedless vascular plant has only stems. It
does not have any leaves or roots. The small
green extensions on the stems are scales,
simple flaps of tissue lacking any vascular
tissue.
Lycopodium
An example of one of the lycophytes
(Div. Lycophyta)
Div. Sphenophyta
• Example: Equisetum ("scouring rush")
• The tiny microphylls are brown. Stem is
photosynthetic
Division Pteridophyta
• Ferns
• Note the large leaves and fuzzy rhizomes
(horizontal stems)
• On the undersurface of the leaves are diskshaped structures bearing many sporangia.
Each dot is a sorus with many sporangia.
Division Coniferophyta
• Pines and conifers
• Seed-bearing vascular plants with strobili
• Leaves in pairs on short shoots
Simple leaves
A simple leaf consists of an undivided
blade or lamina. A petiole or stalk
may or may not attach the blade to
the stem.
Highly lobed leaves may appear to be
compound.
Monocot or dicot?
Check your answer on the other side
of this sheet.
Monocot or dicot?
Monocots have parallel venation in
their leaves and flower parts in
multiples of three.
Dicots have reticulate (netllike)
venation in their leaves and flower
parts in multiples of fours or fives.
Compound leaves
 A compound leaf has a blade that is subdivided into
smaller leaflets. The petiole of a compound leaf is called a
rachis.
 The leaflets of a compound leaf may be connected at a
single point. This type of leaf is palmately compound.
Examples include the leaves of agarito (Berberis trifoliata)
and bluebonnets (Lupinus texensis).
 Pinnately compound leaves have leaflets connected along
at different points along the rachis of the leaf. Examples
include mesquite (Prosopis glandulosa) and Texas
mountain laurel (Sophora secundiflora).
A compound leaf may be
subdivided more than once.
• Once
• Twice
• Thrice
Ball moss (Tillandsia recurvata)
• Use a handlens to examine the hairs on the
narrow leaves. What function do you think
they serve?
Stems
Stems bear leaves, other stems,
flowers, and fruits. The arrangement
of leaves on a stem is its phyllotaxy.
Branch with leaf scars
On plants that shed their leaves, scars
remain on the branches. The scars
are typically below a branch or
axillary bud.
Alternate phyllotaxy
One leaf per node
Opposite phyllotaxy
Two leaves per node
Whorled phyllotaxy
Three or more leaves per node
Long shoots with spur shoots
Most trees and shrubs have only long
shoots (stems). Some, like Ginkgo
biloba or Berberis trifoliata, have
spur shoots as well. Spur shoots
have tightly packed leaves (so the
stems are very short).
Flowers
The degree of compoundness
 A pinnately compound leaf with two rows of leaflets
attached to the main rachis of the leaf is once pinnately
compound. An example is the compound leaf of Texas
mountain laurel (Sophora secundiflora)
 The leaflets may be subdivided even further. If each leaflet
is further subdivided into separate leaflets, the leaf is twice
pinnately compound. An example is the compound leaf of
huisache (Acacia Smallii).
 Thrice pinnately compound leaves are subdivided at the
next level. An example is the compound leaf of heavenly
bamboo (Nandina).
Flowers
• Perfect flowers have both types of
gametophytes, male and female.
• Imperfect flowers have only a single type of
gametophyte.
• Complete flowers have all four whorls of
flower parts: sepals, petals, stamens, and
carpels
• Incomplete flowers lack one or more of the
four whorls of flower parts.
Imperfect flowers
Imperfect flowers produce only one
type of gametophyte (male or
female).
Hypanthium
A hypanthium is a floral cup. The
bases of the sepals, petals, and
stamens fuse to form a cup-like
structure in members of the Rosaceae.
Miscellaneous flowers
• Try to identify the four components of a
complete flower: sepals, petals, stamens,
and carpels.
• The primitive condition for flowers is to
have many free parts (petals, stamens,
carpels) as in this Ranunculus flower.
• The derived condition for flowers is to have
few flowers parts that are fused.
• Fusion of floral parts has occurred in these
flowers.
Inflorescences masquerading as
flowers
• Members of the sunflower family, the
Asteraceae, have many flowers tightly
packed into heads or capitula (sing.
capitulum). The heads function as the unit
of attraction.
Fruits
• A“ripened” ovary. The seeds are fully
mature in a ripe fruit and ready to be
dispersed.
• The ovary wall may have three discernible
layers: the endocarp, mesocarp, and
ectocarp.
• There may be one or multiple chambers
within a fruit.
Simple fruits
• Simple fruits are derived from a single
ovary in a single flower.
• Simple fruits may be dry or fleshy at
maturity. Dry fruits have pericarps (fruit
walls) with very little moisture. Fleshy
fruits have pericarps that contain a good
deal of moisture.
Berry
• The entire pericarp is fleshy.
• It may contain one to many seeds.
• Peppers and tomatoes are derived from
flowers with superior ovaries
• Bananas are derived from flowers with
inferior ovaries
Pome
• Pomes are found in the Rosaceae.
Examples include apples and pears.
• A pome is derived from a flower with a
hypanthium (floral cup).
• In apples and pears, the core is the actual
ripened ovary. The fleshy part we eat is
derived from the hypanthium.
Pepo
• Type of fruit found in the cucumber family
(Cucurbitaceae).
• Derived from a simple, inferior ovary
• Look for scars where the flower parts were
attached.
Hesperidium
• Found in the citrus family (Rutaceae)
• Has a leathery rind with oil glands (the
dots)
• Pulp consists of liquid-filled ovary hairs
Drupe
• Endocarp is hard
• Mesocarp and ectocarp may be fleshy
(plum, peach) or fibrous (coconut)
Coconut
• Drupe
• The “shell” of the coconut is really the
endocarp. The exocarp and mesocarp have
usually been removed by the time it reaches
market.
• The "meat" of the coconut is solidified
endosperm. Coconut "milk" is liquid
endosperm. Endosperm is triploid tissue
derived from fertilization of a binucleate
cell in the female gametophyte by a sperm
from the male gametophyte.
The “pit” of a peach or a plum is the
endocarp. Inside the pit is a seed that
resembles an almond. (But don’t eat it, it
contains cyanide-forming compounds!)
Aggregate Fruits
• An aggregate fruit derived from multiple
carpels within a single flower.
• Examples: strawberry, rose "hips", magnolia
fruits, raspberries
Strawberry
• The "seeds" on the exterior are really
achenes--dry, indehiscent fruits.
• The part we eat is the swollen receptacle
and not part of the ovary at all.
Compound or Multiple Fruits
• A compound fruit is produced from the
ovaries of many flowers.
• Example: Pineapple. Each diamondshaped section of a pineapple represents a
single flower.
Dry Fruits
• Dry fruits are not fleshy at dispersal time.
They fall into two categories: indehiscent
and dehiscent.
• Indehiscent = does not split at maturity,
examples: wafer ash, acorns, achenes such
as the sunflower "seed"
• Dehiscent = split at maturity to release the
seeds, examples: legumes, capsules (such as
found in okra)
Scale-like leaves
• This juniper has scale-like leaves.
Keys for woody plants
• Use these keys to identify the woody plants
before you.