Weeds Gen SP
Total Page：16
File Type：pdf, Size：1020Kb
WEEDS Science Page WEED LIFE CYCLES DID YOU KNOW? Annual weeds Biennial we eds Perennial weeds .usbg.gov Weeds are plants growing complete their live for two live year to year. w life cycle in a growing where they are not wanted. Perennials die ww single season. seasons. to the ground They can quickly grow and take each growing over bare patches of soil. Weed During the first season. But seeds can be buried in the soil growing season, they their for many years. When they are Seeds of annuals make food that underground uncovered, they can still sprout sprout a nd is stored in the ir roots or ste ms and grow. grow into underground stay alive and send up new mature stems or roots. shoots at the plants. In the second After season, they start of the UNITEDSTATES BOTANIC GARDEN Seeds of making use the stored each growing evening seeds, t he food to make season. primrose plants d ie. flowers and can yellow seeds. sprout a nd lambsquarters Queen Anne’s lace nutsedge grow after being buried WEED SEEDS Dandelion in the soil for over 100 Most weeds make seeds have years! lots of seed parachutes s. that float in Weeds also the wind. have unique Burdock evening primrose ways to seeds hitch a spread their ride on fur seeds. and clothing. WEEDS ARE HARDY WEEDS GROW FROM PLANT PARTS Most weeds can Many grow very weeds can Field bindweed grows lots of rapidly, and also sprout roots. New they can grow from roots, A small piece of plants sprout in many stems, or stem or leaf of up from the different places. leaves. common purslane roots. can grow into a fireweed new plant. WEEDS CAN BE FRIENDS... ...AND CAN BE FOES! While weeds can become pests in fields, lawns, and gardens, It can be difficult to get rid of they can also be useful. They can be used as food or medicine weeds, especially in areas for humans and animals. They can protect and improve the where humans have soil. They can also be beautiful to look at! disturbed the soil. Weeds can reduce crop yield in fields and Weeds quickly gardens. sprout and grow on bar e soil, and keep it from Where did all these washi ng or weeds come from? blowin g away. lambsquarters bugleflower gill-over-the-ground Many weeds, such as comfrey, have been used as food and medicine for burdock hundreds of years. Deep-rooted weeds can bring up nutri ents chicory from deep in the soil. When they die, dandelion Weeds compete with crops for space, weeds add organic matter to the soil. water, sunlight, and nutrients. calculate the number of weeds per square meter (or per sq yard) for each soil sample. CROSSWORD PUZZLE 6. Summarize your results on a chart and/or a .usbg.gov graph. For example, you can put soil type on w Across 2. Grows where it is not wanted. the x-axis and weeds/m2 on the y-axis. ww 5. Weeds can be in gardens. 7. Can you think of a hypothesis for why more 7. A plant that lives from year to year. weeds are growing per m2 in one type of soil 9. Completes its life cycle in one season. than in another? How might you test this Down hypothesis? 1. Weeds have many ways to spread . 3. Some weeds can be used as . 1. SPOTLIGHT 4. A plant that lives for two years. ON RESEARCH UNITEDSTATES BOTANIC GARDEN 6. Some weeds can 2. Velvetleaf Seeds Are Not All Alike from roots or stems. Velvetleaf is a large weed that produces 8. Weeds can reduce thousands of seeds. It can cost farmers millions crop . 3. of dollars in lost crop yields. Scientists are 4. 5. studying velvetleaf seeds, so that they can find better ways to control it. In one study, scientists 6. at McGill University in Canada tried to answer 7. 8. these questions: Do large velvetleaf seeds sprout (germinate) better than small ones? Do seeds from one plant sprout better than seeds from another? They randomly picked 10 velvetleaf plants, 9. and then collected up to 1000 seeds from each plant. They separated the seeds from each plant by weight—small, medium, and large. Then they put the seeds in growth chambers. Inside the chambers, the moisture, temperature, and daylight were similar to what one would find TRY THIS outside in the spring. WHERE DO WEEDS COME FROM? More medium-sized seeds sprouted than What you need heavier seeds. Some of the heavier seeds * about 4 liters (1 gallon) of soil from three became dormant, that is, they may sprout at different places, such as a garden, an empty some later time. The percentage sprouting also lot, a roadside, or a lawn depended a lot on which plant the seeds were * 3 growing containers of the same size (about from. 30 cm [1 ft] in diameter) The scientists believe that the differences * hand lens between seeds may help velvetleaf plants * 3 popsicle sticks survive. Different seeds may sprout and grow * paper and pencil better under different conditions. The live but * weed identification book dormant seeds could be a kind of insurance for What to do the velvetleaf plant. Even if all the velvetleaf 1. Use a hand lens to search each soil sample plants in a field die off, the dormant seeds in the for weed seeds. Remove any large stones or soil could sprout later and grow into new plants. debris from the samples. Source: Baloch, H.A., DiTommaso,A., and Watson, A. K.(2001). 2. Punch drainage holes in the bottom of the Intrapopulation variation in Abutilon theophrasti seed mass and its relationship to seed germinability. Seed Science Research. 11, 335- three containers, if needed. 343. 3. Place each soil sample in a container. Use Ha! Ha! the popsicle sticks to label where they came from. Ha! Ha! JOKE 4. Place the containers outside or in a well-lit Knock! Knock! Who’s there? room. Water the soil in each container for a Weed. Weed who? few days until some weed seeds sprout. Try We’d know if you would answer the door! to identify the weed seedlings. 5. Count the number of weeds over a 4-week period or longer, and measure the area of the soil surface in each container. Then .