1: External Features of Stems & Leaves Flashcards by Heidi Sawyer

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

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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

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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

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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

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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

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Define bud scales

The outer protective, waxy coating that surrounds the apical meristem in a dormant bud

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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.

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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

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Define dicot. What kind of leaf venation do they have?

A class of higher plants (Angiosperms) with seeds that have two cotyledons

Netted venation

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Define lenticel

raised pores in the stem of a woody plant that are the site for gas exchange between the atmosphere and plant tissues

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Define internode

The space on the stem that is between nodes (leaf attachments)

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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

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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.

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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

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Define simple leaf

1 of the 2 kinds of leaves with just one leaf blade - the opposite of compound

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What is the margin? what are some examples?

the outline of the leaf or leaflet

lobed
serrated
entire

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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

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Define petiolule

The attachment between the leaflets and the petiole

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Define node

A point on the stem with swelling where a leaf is attached or was once attached

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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

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Define leaf

the primary photosynthetic organ of a plant

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Define leaflet

One of the individual flattened blades or components of a compound leaf that make up the entire leaf blade

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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

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Define midrib

The central vein of a leaf that is raised

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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 1. pinnate 2. palmate 3. 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