The small, triangle-shaped seeds sticking to this shoe are those of beggar lice, or tick-trefoil. They are examples of seeds that are spread by sticking to or hooking onto animal fur and human clothing. JUD MCCRANIE / CREATIVE COMMONS

Plants must spread their ripe seeds

The seeds of countless wildflowers, trees, grasses and other plants are ripening now, if not ripe already.

Now comes another crucial step: seed dispersal. If the seeds don’t spread out, many germinating seedlings will grow very close to each other and to the parent plant, resulting in competition for limited light, space, water and nutrients.

Plants, of course, don’t have the ability to walk or fly. Instead, they rely on various means to spread their seeds several feet to miles away from the parent plant.

Acorns, hickory nuts and other kinds of nuts are spread when squirrels, blue jays and chipmunks bury or cache the nuts to eat later in the season. The creatures fail to retrieve a lot of their stored bounty, though, which then may germinate into new seedlings.

The seeds of cocklebur, tick-trefoil, beggar lice, Spanish needles and other plants can stick or hook onto animal fur and human clothing, allowing the seeds to hitchhike far and wide.

Some plants go ballistic, such as spotted and pale jewelweeds. When touched in late fall, they may violently shoot ripe seeds from their swollen pods. Hence, their other name: Touch-me-not.

Numerous plants, especially inhabitants of meadows and grassy fields, produce seeds with silky, fluffy tufts — called “parachutes” — that float in the wind. They include asters, thistles, goldenrods, milkweeds and others. Seeds of Eastern cottonwood trees also disperse this way.

Several trees, including maples, ashes, elms and tulip trees, produce winged seeds that twirl helicopter-like on the wind away from their parents.

The seeds of fruit- and berry-producing trees are spread when birds and animals eat the seed-laden fruits. The seeds pass intact through the animals’ digestive tracts and are deposited when the creatures defecate.

IN THE SKY: From David Dundee, Tellus Science Museum astronomer: The moon will be first-quarter on Tuesday. Mercury is low in the east just before dawn. Brilliant Venus is very low in the west just after dark and sets an hour later. Mars is in the south at dusk and will appear near the moon on Thursday. Jupiter is low in the west and Saturn is very low in the southwest as the sky darkens. Saturn will appear near the moon on Sunday.

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