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 disk-shaped 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 diamond-shaped 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.