Many things in the green world are seeing explosive growth by the end of this month. That includes cattails.

The long, swordlike new leaves of cattails are up several feet, so marshy areas look quite green. Stands of cattails can also be found along shores of lakes, in river backwaters and in roadside ditches.

Cattails are a great value to aquatic communities. They provide nesting habitat for many marsh birds; shoots and rhizomes are consumed by muskrats and geese; submerged stalks provide spawning habitat for fish and shelter for young fish; and muskrats harvest numerous cattail leaves and plaster them together, creating a lodge with an under­water entrance.

Ancient people collected the cigar-like seed heads on stalks and soaked them in animal fat to use as torches. Cattails continue to have many uses in cultures throughout the world. The leaves are dried and woven into mats and baskets. The down from the spikes can be stripped off and used as stuffing in quilts and pillows, and even in wall insulation.

People past and present have found cattails to be a good source of food. In spring the young shoots, about 4 to 16 inches long, can be easily pulled from the rootstalks, peeled to the tender white core and eaten raw or cooked like asparagus.

Cattails are nature's water purifier. The roots contain an antibiotic substance that attacks and kills fecal bacteria in human and animal waste. Cattails can absorb pollutants such as phenols, cyanide, zinc and hydrogen sulphide.

Jim Gilbert's Nature Notes airs on WCCO Radio at 7:15 a.m. Sundays.