Almost everything you eat started as sunlight on a leaf

Word	What it means
Xylem / phloem	Tubes inside the plant: xylem carries water and nutrients up from the roots; phloem carries sugar from the leaves to the rest of the plant.
Chlorophyll / stomata	The green substance in leaves that captures light / tiny openings, mostly under a leaf, that let carbon dioxide in and oxygen and water vapour out.
Photosynthesis	Making sugar from light, carbon dioxide and water, in the leaves. Plants also carry out respiration, using that sugar for energy, day and night.
Pollination / seed dispersal	Carrying pollen from the part of a flower that makes it, the stamen, to the part that receives it, the pistil / carrying seeds away from the parent plant.
Sexual / asexual reproduction	Making seeds, each a new mix of two parents / growing a new plant from part of one parent, identical to it, also called vegetative reproduction.
Soil texture / humus	A soil's mix of sand (the biggest particles), silt and clay (the smallest); loam has all three / the dark, decomposed remains of living things, which holds water and nutrients.
N, P, K	Nitrogen, phosphorus and potassium, the nutrients a plant needs most. A fertilizer adds them.
Pest / pesticide	Anything that harms a crop — an insect, a weed, a fungus / a chemical that kills it: herbicides kill weeds, insecticides insects, fungicides fungi.
Integrated pest management	Using several methods against pests, and a pesticide only when it is really needed.
Selective breeding / monoculture	Breeding only from the plants with the traits you want, generation after generation / one crop grown over a large area.

Use	Examples
Food	Wheat for flour, barley for animal feed and malt, canola for cooking oil
Fibre	Cotton cloth, linen woven from flax, paper and cardboard from wood
Medicine	ASA (Aspirin) was developed from a pain-relieving substance found in willow bark
Shelter	Lumber and plywood for houses; lodgepole pine poles for tipis

First Nations and Métis knowledge. Long before farms, the peoples of what is now Alberta knew which plants could be eaten, which could heal and which could be built with, and Elders passed that knowledge down over many generations. Saskatoon berries were eaten fresh or dried, and dried berries were sometimes mixed into pemmican — dried meat pounded together with fat — a food that kept for months and fed Métis bison hunters and fur-trade travellers. Birch bark was made into containers and canoes. Many First Nations burn sweetgrass and sage in smudging ceremonies. The lodgepole pine is named for its use as poles for lodges, or tipis. Many of these plants are still gathered and used today.

light energy + carbon dioxide + water → sugar + oxygen

That is photosynthesis, and it happens in the leaves, where the chlorophyll is. The sugar is the plant's food, for energy and for building new roots, stems and leaves.

Worked: a bag on a branch. A clear plastic bag tied over a leafy branch on a sunny afternoon is misty with droplets an hour later. Where did the water come from? It came up from the roots through the xylem, left the leaves through the stomata as vapour — transpiration — and condensed on the plastic. It is not wasted: as water evaporates, it pulls more up the stem behind it, and it cools the leaf, the way sweat cools you.

Flowers and seeds. A bee visiting a flower for nectar picks up pollen from the stamens and brushes some onto the pistil of the next flower. The pollen fertilizes the ovules, tiny parts inside the pistil that become seeds, and the part around them becomes the fruit. Seeds then need to get away from the parent, which would shade them: dandelion seeds ride the wind, burdock burrs hook onto fur, and birds eat saskatoon berries and pass the seeds unharmed.

Without a seed. Strawberry runners take root, and a potato sprouts from its “eyes”. This vegetative reproduction is fast and predictable, but every copy has the same weaknesses.

Soil	Particles	Water and nutrients
Sand	Largest; gritty	Drains fast and dries out; holds few nutrients
Silt	Medium; smooth, like flour	Holds some of each
Clay	Smallest; sticky when wet	Holds a lot of both, but can stay soaked
Loam	A mix of all three, with humus	Holds enough and drains well: best for most crops

Worked: which soil holds water? A student pours 100 mL of water through equal cups of sand, loam and clay, and measures what drains out in five minutes: sand 80 mL, loam 55 mL, clay 25 mL. The water held back is 100 − 80 = 20 mL for sand, 100 − 55 = 45 mL for loam and 100 − 25 = 75 mL for clay. Clay holds the most — but waterlogged clay leaves no room for the air that roots also need, which is why loam, in between, suits most crops.

The black soils of central Alberta are dark with humus, built up over thousands of years as the roots of prairie grasses died and decomposed.

N, P and K. Nitrogen helps leaves and stems grow, phosphorus helps roots, flowers and seeds, and potassium helps the plant resist disease. A fertilizer bag lists them in that order: 20-10-10 means 20% nitrogen. Whatever the crop cannot use is wasted, and can wash into lakes and feed algae.

Without soil. In hydroponics, roots grow in water with nutrients dissolved in it, so a greenhouse can grow lettuce even in an Alberta winter — using energy for its pumps, heat and light.

Selective breeding. In the 1960s and 1970s, Canadian plant breeders took rapeseed and, generation after generation, bred from the plants lowest in two natural substances that made its oil and meal poor for food and animal feed. The result, canola, is now one of Canada's most valuable crops.

Monoculture. One crop across a whole field is efficient to plant, spray and harvest, but a pest or disease that attacks it finds nothing in its way. Clubroot, a disease that swells and damages canola roots, has spread through Alberta fields since the early 2000s. Its spores last for years in the soil, so the best defences are crop rotation — growing wheat, barley or peas in between canola years — and canola bred to resist it.

Integrated pest management. Spraying on a schedule also kills insects that were not pests — including the ladybugs and wasps that eat pests — and pests sprayed over and over can become resistant. So the farmer counts first, sprays only when it is worth it, and uses other tools too: crop rotation, resistant varieties, natural predators.

Worked. Small holes in young canola leaves mean flea beetles. Before spraying, the farmer checks how much leaf is being eaten across the field. A little, and spraying would cost more than it saves; heavy and spreading, and spraying now protects the crop. The count decides, not the calendar.

Keeping the soil. In the 1930s, drought and wind blew the topsoil off ploughed prairie fields. Many farmers now plant straight into last year's stubble without ploughing, called zero tillage, which keeps the soil covered and in place.

• Saying a plant gets its food from the soil. It makes sugar in its leaves from air and water; soil supplies water and nutrients.
• Swapping xylem and phloem. Xylem carries water up; phloem carries sugar around.
• Saying plants photosynthesize instead of respiring. They do both; respiration never stops.
• Mixing up pollination and seed dispersal. One moves pollen; the other moves seeds.
• Assuming the soil that holds the most water is best. Roots need air too.
• Assuming more fertilizer or pesticide is better. Past what the crop needs, it is wasted or harmful.