Adaptations for Spreading Seeds

Life Science - Middle School

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Even after a plant is pollinated and fertilized, it has not completed its life cycle. It still must spread its seeds out into the world. This is called seed dispersal. Spreading seeds is important for the plant to pass on its own traits, but it is also a challenge. Seeds need sunlight, soil and water to grow, but parent plants that live for more than one season do not want to share their space. So, many plants have adapted seeds that move away from home before they begin to grow. The seeds of the sugar maple and elm tree grow with a flat propeller, called a samara (1). When they fall from the tree, their shape makes them helicopter away. A basswood tree’s seed has a long, flat attached wing that spins away in the wind. Some plants, like fuzzy goatsbeard and dandelions, grow a globe of fluff that breaks off in the wind into a mass of parachutes called achenes (2), each holding one seed. Sometimes seeds burst from a pod (3) like the milkweed, or pull out in the wind like a thistle, and their seeds float away on silken strands. Plants even get animals to carry their seeds by growing fleshy fruits (4) around the seeds, like apples, berries and even acorns. Animals eat the seeds and, after they have gone through their digestive tract, they deposit the seeds in a new location in their scat. This works especially well with animals like squirrels and chipmunks who collect the seeds and hide them for later use by burying them in the ground or under a pile of leaves. This is not only spreading the seeds but getting them planted as well. Whether by wind or by beast, seed dispersal is an important step in a plant’s life cycle. Adaptations for Spreading Seeds 4 1 3 2 4
Even after a plant is pollinated and fertilized, it has not completed its life cycle. It still must _____________________________ its seeds out into the world. This is called seed dispersal. Spreading seeds is important for the plant to pass on its own ______________________________, but it is also a challenge. Seeds need sunlight, soil and __________________________ to grow, but parent plants that live for more than one season do not want to share their space. So, many plants have adapted seeds that move away from home before they begin to grow. The seeds of the sugar maple and elm tree grow with a flat propeller, called a __________________________________(1). When they fall from the tree, their shape makes them helicopter away. Some plants, like fuzzy goatsbeard and dandelions, grow a globe of fluff that breaks off in the wind into a mass of parachutes called ______________________(2), each holding one seed. Sometimes seeds burst from a ________________(3) like the milkweed, or pull out in the wind like a thistle, and their seeds float away on silken strands. Plants even get animals to carry off their seeds by growing fleshy _________________________(4) around the seeds, like apples, berries and even acorns. Animals eat the seeds and, after they have gone through their digestive tract, they deposit the seeds in a new location in their scat. This works especially well with animals like squirrels and chipmunks who collect the seeds and hide them for later use by burying them in the ground or under a pile of leaves. This is not only spreading the seeds, but getting them planted as well. Whether by _______________________ or by beast, seed dispersal is an important step in a plant’s life cycle. 4 4 1 3 2 94-4047 Adaptations for Spreading Seeds