Help students puzzle out
what plant parts they
munch at lunch!
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Plants come in all shapes and sizes, from
cacti to trees and orchids to gourds, but they all possess common parts that
carry out similar functions. These parts may vary greatly in appearance and
number. This variety is the result of adaptations to various niches in the
environment, and it makes for a great palette of plants for gardeners to grow
and enjoy. The following is an overview of common plant parts.
Vegetative Plant Parts: Roots, Stems and Leaves
Roots. A plant can't thrive above ground without healthy roots below
the ground. There are two main types: taproots and fibrous roots. Taproots
(think
of a carrot) feature a large primary structure with a few smaller secondary
roots. Many lawn grasses feature fibrous roots that appear as a clump of many
similar-sized structures. Both types are covered with tiny root hairs
that absorb water, along with dissolved nutrients, from the soil. Plants move
the
water from the roots up through the stems to their leaves. Some plants feature
specialized roots that, in addition to their normal role, store food for future
plant growth. The sweet potato is this type of root.
Discuss the different parts of the plant using the plant part diagram.
Every day we eat foods representing different plant parts. Brainstorm
with students to create a list of common foods representing each part. Here
are a few ideas to get you started:
roots — carrots, sweet potatoes
stems — asparagus
leaves — lettuce, spinach
flowers — broccoli, cauliflower
fruits — tomatoes, apples, bananas, cucumbers
seeds — corn, peas, nuts, rice
Next, explore today's school lunch and identify all the plant-derived
ingredients used. Determine what part of the plant each ingredient represents.
For example, for a lunch including pizza, salad, and an oatmeal cookie:
Pizza:
Tomatoes — fruit
Wheat flour — seeds
Basil — leaves
Oregano — leaves
Salad:
Lettuce — leaves
Carrots — roots
Cucumbers — fruit
Oatmeal Cookie:
Raisin (grape) — fruit
Oats — seeds
Sugar (sugar cane) — stems
As a follow up, ask each student to plan a menu that includes food derived
from a variety of plant parts.
Leaves house a plant's food factories. Plants have the special ability to produce their own food through a process called photosynthesis. Inside the plant cells are chloroplasts, which use carbon dioxide, water, chlorophyll (the green pigment in plants), and sunlight to make sugars/carbohydrate. This is what fuels plant growth. A plant without leaves does not have the energy to continue living unless it is dormant or has enough food stored in other parts (like that sweet potato root). Leaves also transpire (emit water, kind of like sweating) to maintain a plant's healthy temperature and encourage roots to continue absorbing water.
Stems contain a transport system — something like our own veins and arteries — that allows water and nutrients to move throughout the plant. Xylem cells transport water and dissolved nutrients from the roots to the leaves, and phloem cells move the food produced in the leaves during photosynthesis to other parts of the plant. Stems tem also supports the plant form the backbone of growth.
Reproductive Plant Parts
The reproductive parts of plants are even more varied than vegetative parts — that's what makes our flower gardens so beautiful. Most plants produce flowers that then develop fruit and seeds (exceptions include ferns and conifers like pine trees).
Flowers exist to produce the next generation and help ensure a species' survival. Most flowers contain a female organ, the pistil (usually just one, though there some species feature more than one) and male organs, the stamens (usually more than one). In order to make seeds, pollen produced by stamens must reach the pistil — this is called pollination, which leads to the development of seeds. Most flowers have both male and female parts and are located on the same plant, but there are exceptions — cucumber and squash plants have distinctive male and female flowers.
Seeds grow into new plants. Each seed has a coat surrounding an embryo that contains tiny leaves, a stem, and roots. To ensure survival and success of the species, seeds have evolved different mechanisms get around. For example, maple seeds have wings to help them glide through the air, coconuts can float in water, and milkweed seeds float on "parachutes" of silvery, silky fluff.
Fruits are nature's special packages for seeds. They begin to develop after the flower is pollinated. The fruit can protect the seed as well as aid in transportation. Animals transport seeds by eating the fruits and then leaving the seeds in their droppings — seed and fertilizer in a single package!
Many items we call vegetables are actually plant fruits (tomatoes, cucumbers, squash). From a botanical standpoint, vegetables are foods that come from plants' vegetative parts: stems, roots, and leaves. But these strict definitions are not used in everyday life; some items are called vegetables if they are commonly eaten with the main course of a meal, like the examples above.
