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airborne seeds

Airborne seeds

Some plants are able to plant their own seeds! Ivy-leaved toadflax grows in the crevices of walls. Once its long flower stalks have been pollinated, the seed heads bend towards the wall’s surface, shedding seeds into new cracks. This is known as blastochory.

Trees may not be able to move, but some are good at procuring the services of animals that can.

Trees have a bit of a problem on their hands. If their seeds are to stand a good chance of survival, they need to spread them to new locations out of the parent tree’s shadow. But how do they achieve this without moving parts?

By force (known as ballochory)

Credit: Duncan Mcewan /

Horse chestnut seeds are contained within prickly protective cases.

Each gorse seed pod contains two or three shiny black seeds.

Allochory: spreading seeds with outside help

One of the more unusual ways to spread seeds is to expel them by force. The seeds of gorse are contained within pods which slowly dry out in warm, sunny weather. Once enough moisture has evaporated the pod splits open, flinging the seeds inside some distance.

Fruit-bearing trees such as rowan offer birds a tasty reward for carrying off their seeds. Encased in nutritious, brightly coloured pulp, some may be plucked from the tree and dropped en route to a new location. Other berries are eaten, and an indigestible coating protects the seed inside as it travels through the digestive system. Once the seed exits it may be far from the parent tree, and deposited in a handy dollop of fertiliser too.

When rain rushes down the street and splashes into your lawn, it may be bringing weed seeds along with it. Lawnmowers spread seeds, and poor-quality lawn seeds, mulch, potting soil and straw can also contain weed seeds.

Shady lawn – Any spot that’s too shady for grass to grow is a potential haven for lawn weeds. If possible, trim trees to let more light shine on the lawn. Otherwise, shift from grass to shade-tolerant ground covers to fill in soil and keep weeds at bay.

In your own yard, establish a weed patrol by keeping an eye on the following weed “resorts,” which offer ideal conditions for plants to grow and reproduce.

Where do weeds hide?

Unpaved parking areas – Whether such an area is grassy, muddy or filled with gravel, it rolls out the welcome mat for weeds. Gravel especially offers quick drainage, which provides a perfect seedbed for plants.

Cracks and spaces – Every crack between paving stones or slabs of concrete provides ideal footing for weeds. Even cracks in concrete driveways filled with joint compound can collect enough soil to sprout weed seedlings.

Beneath shrubs – Areas under shrubs can be hard to reach and may also be shady and moist, a perfect place for weeds to take root and thrive in secret.

Under decks – You’d think sparse sunlight would make weeds run for cover, but they seem to thrive beneath decks.