1: Plant Morphology (3/31) Flashcards
Herbs
Plants whose above-ground growth is mostly herbaceous (non-woody) and therefore dies back at the end of the growing season
Woody perennials
Produce woody stems that persist for multiple years
Can be shrubs or trees
Leaf axil
The angle between the leaf base and the stem
Bud
Very young shoot tissue that may become a branch or an inflorescence
Bud scales
The small, brownish, overlapping structures that cover the over-wintering buds of woody plants and are modified leaves
Cauline leaves
Grow directly on the stem and are attached without a petiole (stalk)
Phyllotaxis
What does this word mean?
The arrangement of leaves on a plant stem
Alternate leaf arrangement
When a single leaf grows at each node along a stem, with leaves alternating sides as they progress up the stem
Opposite leaf arrangement
Where two leaves grow at the same node, directly across from each other
Whorled leaf arrangement
Three or more leaves grow at a single node
Fasciculate leaf arrangement
Leaves that are clustered together in small, tight bundles (fascicles) along a stem or branch
ex: conifers
Basal leaf arrangement
Leaves that grow in a rosette or cluster at the base of a plant
ex: dandelion and plantain
Difference between 2- and 4-ranked leaf arrangements
2-ranked: leaves are formed in two vertical rows on opposite sides of the stem, forming a flattened, 2-dimensional appearance
4-ranked: leaves are arranged in four vertical rows around the stem, with each successive pair of leaves rotated 90° from the previous pair
2-ranked: grasses and corn
4-ranked: basil
Adaxial
Upper surface of the leaf (or ventral)
Abaxial
Lower surface of the leaf (dorsal)
Stipule
A small leaflike appendage to a leaf (like at the base of the petiole)
Leaf venation
What are the 3 different types and what distinguishes them?
Pinnate
Parallel
Palmate
Pinnate: A single central midrib runs down the leaf, with smaller veins branching off like a feather
Parallel: Veins run parallel to each other from the base to the tip
Palmate: Several main veins spread out from a single point, resembling fingers on a hand
Leaf blade division
What are the options for how a leaf can be divided?
Entire
Palmate, pinnate, teeth
Entire: no lobes or teeth
Pinnate: sinuses reach inward toward the single vein
Palmate: sinuses reach inward in between two veins (maple leaves)
Palmate and pinnate differences for veins
Palmate: Several main veins originating from a single point
Pinnate: Single main vein
Peduncle
The stalk of an entire inflorescence
Pedicel
The stalk of a single flower within an inflorescence of more than one flower. If the flower lacks pedicels it’s sessile
Solitary flower
An inflorescence consisting of one flower, either terminal (on end of stem) or axillary (on axil of leaf)
Scape
A peduncle arising from ground-level (often from a rosette of basal leaves) either terminating in a solitary flower or a flower cluster
Bract
Modified (reduced) leafs that occur in the inflorescence
Involucre
Cluster of bracts
Determinate (cymose) inflorescence
The main axis, as well as each branch of the inflorescence, terminates in a flower, halting main axis growth; oldest flowers are at the top or in the middle
Indeterminate (racemose) inflorescence
The main axis and branches continue to grow; oldest flowers are at the bottom or outside
Helicoid inflorescence
Inflorescence branches on alternating sides
Scorpioid inflorescence
Inflorescence branches on one side
Indeterminate umbel
A flower cluster where multiple flower stalks (pedicels) radiate out from a single point. Oldest flowers are towards the outside of the inflorescence
Determinate umbel
A flower cluster where multiple flower stalks (pedicels) radiate out from a single point. Oldest flowers are towards the center of the inflorescence
Head inflorescence
Where multiple flowers are arranged on a short, dense spike, giving the appearance of a single flower
ex: sunflower
Glomerule inflorescence
Characterized by a dense, head-like cluster of sessile or subsessile (very small pedicel) flowers
Fascicle inflorescence
Characterized by a dense, head-like cluster of flowers with pedicels
Rachis
The central axis around which leaflets are arranged on a compound leaf
Stem succulents
What modification do they have and what is its purpose?
Have stems that are modified for water storage
Rosettes
Stems that have very short internodes with many leaves clustered together
Stolon
A horizontal, above-ground stem that grows along the surface of the soil and can produce new plants (clones) at its nodes or tips
Rhizomes
Usually horizontal stems that travel beneath the ground
Corms
Very short, upright, underground storage stems
Tubers
Enlarged underground storage stems
Ex: potatoes
Bulbs
Very short, upright, underground stems with very short nodes bearing fleshy storage leaves or buds
Ex: onions and garlic
Primary root
The first root that develops on a seedling
Tap root system
The tap root and its lateral roots
Fibrous root system
Characterized by a dense network of thin, branching roots that arise from the stem rather than a taproot
Lamina
Leaf blade
Compound leaf
A leaf where there are several leaflets joined to a single stem
Palmately compound leaf
A compound leaf where all the leaflets attach to the same point
Pinnately compound leaf
A compound leaf where all the leaflets are arranged along the rachis
Odd-pinnate
On a compound leaf
Has a terminal leaflet
Even-pinnate
On a compound leaf
Lacks a terminal leaflet
How can you describe how many times a compound leaf is subdivided?
1-pinnate (once compound)
2-pinnate (twice compound)
…and so on
Palmately trifoliolate compound leaf
Compound leaf with three leaflets and no rachis
Pinnately trifoliolate compound leaf
Compound leaf with three leaflets and a rachis
