Hort 1001 Lecture 8

Front 1

Roots

Back 1

Roots anchor plants, support upright growth, serve as a site of symbiotic relationship, absorb water and minerals and store nutrients.

Front 2

Angiosperms have ___ types of roots.

Back 2

Angiosperms have TWO types of roots.

Front 3

Angiosperm

Back 3

Flowering plant

Front 4

Tap/Primary Root

Back 4

Roots arise as a continuation of the embryonic radicle tissue and persist into maturity.

Front 5

Fibrous/Adventitious Root

Back 5

In plants of this type, the primary root originates from the radicle, weakens prior to maturity and new adventitious roots arise from stem tissue.

Front 6

True or False: Adventitious roots originate from the stem but always emerge from a node.

Back 6

False: Adventitious roots originate from the stem and DO NOT have to emerge from a node.

Front 7

Root Cap

Back 7

Covers tip of the root and provides protection as the root drives into the soil. The outer cells are always wearing away and new cells are always added to the inner portion.

Front 8

The root cap is produced by what?

Back 8

Apical meristem

Front 9

Root Apical Meristem

Back 9

Divide rapidly to form new stems

Front 10

What are the two functions of root apical meristem cells?

Back 10

1: Some lay toward the root cap to replace worn cells

2: Some lay away from the root cap, elongate and then mature into more specialized tissues

Front 11

Region/Zone of Elongation

Back 11

Cells previously produced by the root apical meristem undergo rapid elongation

Front 12

Root growth is the result of 2 processes. What are they?

Back 12

1. New production of cells through the apical meristem

2. Elongation of new cells

Front 13

In the region of elongation behind the meristem, there are 3 types of tissue that can be found. Name them.

Back 13

1. Protoderm

2. Procambium

3. Ground Meristem

Front 14

Protoderm

Back 14

Laid toward exterior of root and become root dermal tissue (usually epidermis cells)

Front 15

Procambium

Back 15

Located in central part of the root and mature to become vascular tissue

Front 16

Ground Meristem

Back 16

Located between the protoderm and procambium that mature to become cortex tissue (usually parenchyma)

Front 17

Region of Differentiation (Region of Maturation)

Back 17

Here, the root becomes thicker and secondary or lateral roots are initiated. The protoderm, procambium and ground meristem cells undergo differentiation into specialized cells. Root hairs also form here.

Front 18

Root Epidermis

Back 18

One-cell thick layer of cells surrounding the root.

Remember: NO CUTIN (WAX) COATING UNLIKE SHOOT! This is because roots do not need to be permeable to moisture!

Front 19

Cortex

Back 19

Cells in the epidermis comprise the cortex. The cortex consists of parenchyma cells with numerous intercellular spaces through which water can move.

Front 20

Endodermis

Back 20

Innermost cells of the cortex

Front 21

The Casparian Strip

Back 21

Thick band of suberin that closes up the intercellular space between cells.

Front 22

What are the "Big 3" in terms of the Cortex?

Back 22

1. Allows diffusion of water, minerals and oxygen from root hairs inwards

2. Stores food reserves (especially starch)

3. Endodermis, with the aid of Casparian strips, facilitate the regulated movement of water from cortex to xylem

Front 23

Vascular Cylinder (Stele)

Back 23

Begins just inside the endodermis

Front 24

Pericycle Cells

Back 24

A set of cells in the vascular cylinder. They retain the ability to divide and produce new cells and are the source of lateral roots.

Front 25

What are the two sets of cells found in a vascular cylinder?

Back 25

1. Pericycle Cells

2. Xylem and Phloem

Front 26

Xylem and Phloem in Dicot Root

Back 26

Xylem is in the center of the root and has an X shape. Not all dicots have the xylem in an obvious X shape, in some cases it looks more round.

Tip - Xs have two lines, and the root "di" means two.

Front 27

Xylem and Phloem in Monocot Root

Back 27

Xylem is in a ring surrounded by phloem with pith in very middle.

Front 28

Apical meristem is located at ___ of the growing shoot and is the site of new ___ division.

Back 28

Apical meristem is located at TIP of the growing shoot and is the site of new CELL division.

Front 29

Herbaceous plants

Back 29

Aboveground plant parts die back to the soil at the end of the growing season.

Front 30

Do herbaceous stems thicken much?

Back 30

Herbaceous stems do not thicken much and rely on branching to grow laterally.

Front 31

What does growth in diameter depend on?

Back 31

Continued growth in diameter (like a tree) requires an active lateral meristem called the cambium - located between xylem and phloem.

Front 32

Cambium

Back 32

Provides growth in diameter and is located between the xylem and phloem.

Front 33

Perennial herbaceous plants store nutrients in the ___ for the next season’s growth. Then in the spring, new shoots emerge from ___.

Back 33

Perennial herbaceous plants store nutrients in the ROOTS for the next season’s growth. Then in the spring, new shoots emerge from NODES.

Front 34

What are the three components of vascular bundles going from the outside to the inside?

Back 34

1. Phloem

2. Cambium

3. Xylem

Front 35

Somana with guard cells are found in the epidermis. What is their function?

Back 35

Their function is to allow gases in and out of the stem.

Front 36

Pith

Back 36

The pith ocupies central part of the stem and is composed of thin-walled parenchyma cells with larger intercellular spaces than those found in the cortex

Front 37

True or False: Cambium is in dicot stems and is active for a while and produces some xylem and phloem which gives the sunflower its larger diameter stem. It is not continually active because the sunflower dies in the winter.

Back 37

True

Front 38

True or False: Tissues in monocots are completely different than those found in dicots.

Back 38

False: Tissues in monocots are virtually the same as those found in dicots.

Front 39

What is the main difference between tissues in monocots and dicots?

Back 39

The main difference is that in monocots, the vascular bundles are scattered throughout the stem and NOT oriented in a ring like dicots. Tend to be more concentrated towards the outside (see picture below).

Front 40

Complete the table

Back 40

Front 41

In monocot vascular bundles, cambium and secondary growth are ____.

Back 41

In monocot vascular bundles, cambium and secondary growth are NON-EXISTENT.

Front 42

Bundle Sheath

Back 42

Layer of parenchyma cells outside of the vascular bundle