Christine Osterhues, age 12, of Huntington Beach, Calif., for her question:

WHERE DO TUMBLEWEEDS COME FROM?

Tumbleweeds roll around Costa Mesa, Calif., in the fall, usually blown by the Santa Ana winds. They arrive from who knows where, looking like large beach balls made of dry brown twigs. Along they roll, resting on lawns and piling up against the fences. Obviously they came from somewhere, even though we did not notice them.

Actually the tumbleweeds spent the summer season growing in the fields and along the roadsides.. Then they were fairly large green bushy weeds. Later in the summer they put on flowers, too small to notice, and the flowers became seeds. Then the weeds dried up their stems, broke off close to the ground  and waited for the wind to blow them along. A tumbling tumbleweed is really a parent plant rolling along to scatter its seeds in new locations.