1: External Features of Stems & Leaves Flashcards
Define annual and give an example
A plant that grows from a seed, flowers and sets seed then dies within a single growing season. This can also be called a bedding plant
ex. pansies
Define perennial and give an example
Plants that have indeterminate lifespans and flower every year once mature, they come back each year.
ex. Any tree
Define biennial and give an example
A group of plants that complete their life cycle in 2 growing seasons. With vegetative growth in the first year, then flowers and sets seed in the second year. Entire life cycle lasts 2 years.
ex. Dianthus (Sweet William) flowers
Define axillary/lateral bud
Buds occurring along the stem that are not the terminal bud. They are where a leaf blade is/was attached and they are called axillary or lateral buds because they grow at a lateral/axillary angle off the stem
What are the two kinds of woody perennials? describe them and give an example
- Deciduous: shoots will drop leaves each fall
- ex. Red Maple trees - Coniferous (evergreen): shoots keep leaves over winter
- ex. Pine trees
Define bud scales
The outer protective, waxy coating that surrounds the apical meristem in a dormant bud
Define terminal bud scale scars. What purpose can they serve in identification?
A ring of scars produced by the bud scales being torn off as the bud expands in the spring time.
The number of bud scale scars that appear from tip down to main stem can determine the years of growth.
Define compound leaf and what feature is used to determine?
A leaf where the blade is composed of two or more individual pieces called leaflets and each leaflet is attached to the petiole via either a rachis (pinnate arrangement) or petiolules (palmate arrangement).
This can be determined by looking for the petiole and whether there is an axillary bud attached at the end
Define dicot. What kind of leaf venation do they have?
A class of higher plants (Angiosperms) with seeds that have two cotyledons
Netted venation
Define lenticel
raised pores in the stem of a woody plant that are the site for gas exchange between the atmosphere and plant tissues
Define internode
The space on the stem that is between nodes (leaf attachments)
Define monocot. What kind of venation do their leaves have?
A class of higher plants (angiosperms) with seeds that have a single cotyledon
parallel venation
Define leaf blade
The flattened part of a leaf that is specialized in photosynthesis. It is the entire compound structure that is made up of leaflets and is attached to the branch via a petiole and axillary bud.
Define pinnately compound
The arrangement of leaflets on a leaf blade that radiate from the rachis in a manner that looks like feathers on an arrow
Define simple leaf
1 of the 2 kinds of leaves with just one leaf blade - the opposite of compound
What is the margin? what are some examples?
the outline of the leaf or leaflet
- lobed
- serrated
- entire
What is the difference between a midrib and a rachis?
a MIDRIB is found within a leaf blade of a simple leaf or the individual leaflets of a compound leaf blade. Whereas,
a RACHIS is found only in pinnately-compound leaves
Define petiolule
The attachment between the leaflets and the petiole
Define node
A point on the stem with swelling where a leaf is attached or was once attached
Define leaf scar. What is inside the leaf scar?
The scar that is left on the stem where a leaf was once attached. Inside the leaf scar there are vascular bundle scars
Define leaf
the primary photosynthetic organ of a plant
Define leaflet
One of the individual flattened blades or components of a compound leaf that make up the entire leaf blade
Define lobed margin. Give an example of a plant with a lobed leaf blade
A lobed margin is when the leaf blade has rounded bumps
Example: Garry Oak leaves
Define midrib
The central vein of a leaf that is raised
Define netted venation. What are the two kinds? And is this found in dicots or monocots?
When the venation on a leaf is intertwined rather than parallel
Can be either palmate venation or pinnate venation
This is found in dicots
What is opposite leaf arrangement?
When two leaves are attached to the same area of the stem but on opposite sides
Define palmate venation
A kind of netted venation when leaf venation radiates from the site where the petiole joins the leaf blade
Define palmately compound
When the leaflets are arranged in a way that radiates from the same point on the petiole
ex. Cannabis leaves
Define parallel venation, what kind of plants (monocot or dicot) is this found in?
The major veins run parallel to the midrib and each other.
Found in monocots like grasses, sedges, and rushes
Define petiole
The stem-like structure that attaches a leaf blade to a stem
Define petiolule
The stem-like structure that attaches a leaflet to a rachis or the petiole in compound leaves
Define pinnate venation
A kind of netted venation where the veins in a leaf blade radiate from the central midrib in a way that looks like feathers on an arrow
Define pith
The central portion of a stem
Define rachis
The central, stem-like axis of a pinnately-compound leaf that extends from the petiole to the end of the leaf blade
rachis means spine or ridge
Define sheath
The part of a grass leaf that wraps around the flowering, jointed and usually hollow stalk of grasses (culm)
Define stipule
A modified leaf that grows at the junction of leaves and the stem
Define terminal bud
The bud on the youngest, apical portion of a stem/shoot - where the new growth will occur
Define vascular bundle scars
Scars within the leaf scar that mark where the vascular bundles were when the leaf was attached to the stem
Define venation and what are the 3 kinds
Venation is the pattern of the major veins within a leaf blade
- pinnate
- palmate
- parallel
Define whorled leaf arrangement
leaf arrangement where 3+ leaves are attached to the stem at one node, generally all around the stem
What are some common kinds of leaf arrangements?
- opposite
- alternate
- whorled
- basal
Define basal leaf arrangement
leaf arrangement where the leaves are attached at the base of the stem
ex. dandelion
What are the common kinds of leaf attachments?
- petiolate
- sessile
- sheathing
- decurrent
What are the common kinds of leaf margins?
- lobed
- serrated
- entire
- crenate
- spinose
Define evergreen herb
A nonwoody plant that remains green and does not die back during winter
Define evergreen
a plant that remains green in the winter
T or F: the term evergreen distinguishes whether a plant is herbaceous or woody?
FALSE. Both woody and herbaceous plants can be evergreens
Define herbaceous
plants characterized by the lack of woody tissue
- many herb. perennials die back to the ground and resume growth in the spring from their perennial organs such as roots, tubers, or rhizomes
What is the dormant growing point between the stem and leaf?
Axillary/lateral bud
What kind of leaf has a blade divided into pieces?
compound
What are the individual pieces of a blade in a compound leaf called?
leaflets
What is the kind of venation that occurs when minor veins that crisscross within the leaf blade of a dicot?
Netted venation
What is the top most bud on a stem called?
terminal bud
What is the stem-like connection of a leaf blade that connects the pieces of a compound leaf?
rachis
What are the flat, green portions of a leaf called?
leaf blades
What are the vascular marks within a leaf scar called?
Vascular bundle scars
what is the vascular system that carries fluids in a leaf blade?
Veins
What are the ring marks that appear on a woody stem when the bud expands in the spring?
Bud scale scars
What is the mark on a woody stem where a leaf has fallen off called?
leaf scar
What are the “breathing holes” on the surface of a woody stem called?
Lenticels
What is the small appendage attached at the base of a petiole in some plants called?
stipule
What is the stalk-like base of a leaf called?
petiole
What is the main stem that runs the length of a leaf blade called?
midrib
What is it called when a leaf blade is in one piece?
simple
What kind of venation is it when the veins run the length of a leaf without crossing?
parallel venation
What is a non-woody stem or plant part called?
herbaceous
What is the section of stem called that is between leaf/bud attachments?
internodes
What is the section of stem called that runs between two leaves that are attached in an alternate pattern?
internode
T or F: the leaves of dicot plants have netted venation?
TRUE
What bud type forms at the tip of each stem?
terminal buds
T or F: Terminal buds are always found at the tip/apex of a stem?
TRUE
T or F: there can sometimes be more than one terminal bud depending on the plant species?
TRUE
What is the botanical term for the “growing point” of a stem?
apical meristem
What are the marks called that remain on the stem, usually in a ring formation, after the bud breaks in the spring?
bud scale scars
What happens to form the bud scale scars?
the base of each bud scale that covered the dormant bud during the winter tears off and leaves a scar on the stem when the bud expands in the spring
What is the central stem-like “backbone” of a COMPOUND leaf to which “pieces” of a leaf blade are attached?
rachis
What is the function of a rachis and where is it located?
it is a stem-like piece that holds the leaflets (like a spine holds ribs) and it starts at the bottom leaflet and runs to the base of the terminal bud
what stem-like part of a leaf attaches the flat green part to the stem?
petiole
What are the small marks called that are left inside a leaf scar after a leaf falls off in the fall?
Vascular bundle scars
What is the flat green part divided into in a compound leaf?
leaflets
Define grasses - which family do they belong to?
Grasses are monocots with simple leaves that have parallel venation. They are herbaceous stems with nodes and leaf sheaths
Poaceae family
Define rushes - which family do they belong to?
Grass-like plants with stems that are not jointed (NO NODES), but are still hollow. Their leaves are usually just small sheathes, but some can have blades and appear like grasses
Juncaceae family
Define sedges - which family do they belong to?
Grass-like plants with triangular shaped stems (or a folded V shape) with a solid pith and no joints. Most blades are flattened but some can look grass like with nodes and alternating leaves
Cyperaceae family
What are the main differences between grasses, rushes, and sedges?
GRASSES: have nodes, leaf sheathes, and circular stems
RUSHES: do not have nodes, have sheathes, circular stems
SEDGES: do not have nodes, have solid pith, triangular shaped stem, generally flattened blades
Define culm, which plants have these?
Grasses, sedges, and rushes
In the winter what will you find on the surface of the stem directly beneath each bud of a deciduous tree? Why?
leaf scars because a leaf is always attached to the stem just below a bud. When the leaf falls off, a leaf scar appears below the bed where the leaf once was.
What is the thick vein that runs down the centre of a pinnately veined leaf blade called?
Midrib
how do temperate shrubs and trees protect their dormant buds through the winter?
Buds are covered with bud scales
Where on the stem would a leaf or leaves and a bud or buds be attached?
Nodes. These are the sections of the stem where both a bud and a leaf are attached
What part of the plant is folded up under the bud scales of an axillary bud that will become the photosynthetic unit when the bud expands in the spring?
Immature leaves
What is the function of the midrib?
It surrounds the main vein that carries water into the leaf and sugar out of the leaf
What are the five plant types?
annuals biennials perennials grass like bulb like
How can you test if a stem is woody or herbaceous?
if you can scrape the centre of the stem out, it has a PITH which means it is herbaceous.
This will not be possible if it’s woody because woody plants do not have piths
