ENVS 201 Spring Quarter 2012

Northwest Indian College

Welcome to Northwest Plants

Plant Parts

stems

roots

leaves

flowers

fruits

seeds

vegetative organs:

reproductive components:

Today:Roots

bean seedling (Phaseolus) showing root system

Root Features & Functions

anchor plants to substrate (e.g., soil)

water and nutrient uptake

may be variously modified (e.g., adventitious roots, food storage, etc.)

interactions with soil, microorganisms (in root nodules) and fungi (mycorrhizae)

adventitious roots (in Coleus)

roots modified for food storage

Beet (Beta)

sweet potato (Ipomoea)

Carrot (Daucus)

mycorrhizal root

hogpeanut (Amphicarpaea bracteata) with root nodules

root cells of pea (Pisum) in root nodules (infected with Rhizobium)

bacterium—>

root cell—>

Root Features

primary root - the main root of the root system

secondary root - a branch root

rootlet - a small root

root nodule - swelling produced by bacteria (e.g., in legumes), site of nitrogen-fixing bacteria (Rhizobium)

Root Types

taproot system (common in eudicots, e.g., dandelion, burdock & carrot)fibrous root system (monocots, e.g., grasses, and some eudicots)adventitious roots (e.g., Coleus)

taproots of burdock (Arctium) & dandelion

(Taraxacum)

Root Regions

root apical meristem - produces cells that lengthen roots

root hair - outgrowth of outer cell of root, extends absorbing region of root

root tip - tip (apex) of a young root

root cap - mass of cells at root tip, protective & maintains downward growth

root lateral meristem (vascular cambium) - produces cells that thicken roots, vascular tissues

root l.s. showing root tip<—apical

meristem

<—root cap

root tip

root hairs (in grass seedling)

basswood (Tilia) lateral meristem (vascular cambium)

vascular—> cambium

Questions & Comments?

Rootsarecool.

Hy’shqe!