麻豆影院

Invasive propensities of the various species are enhanced and more successful in disturbed environments

Marshes ringed with cattails provide entertaining viewing opportunities in spring, when redwing blackbirds, yellow-headed blackbirds, Canada geese, mallards and many other bird species are nesting among the reeds.听

The densely packed, territorial redwing and yellow-headed blackbirds defend their territories valiantly by patrolling and calling from their territorial boundaries.听听While the bedlam set up by libidinous males naturally attracts attention first, the cattails are also of considerable interest.听

Four species of cattails occur in Colorado. All are in the genus听Typha, all are tall (six to 12 feet in height}, herbaceous, perennial, rhizomatous species obligately tied to slow water in marshes, pond and streams. They reproduce sexually, releasing numerous plumed seeds distributed by wind, and asexually with spreading rhizomes.听

Broadleaf cattail,听T. latifolia, is a native species and it seems to be the most common locally. Southern cattail,听T. domingensis, is native to the southern United States and Mexico.听

Narrowleaf cattail,听T. angustifolia, is native to Asia, and was probably introduced to the east coast and is invasive in North America, continually expanding its range. It has spread across the continent but has not yet established in Arizona, Utah or Idaho.听

Hybrid cattail,听T. x glauca, is a hybrid resulting from a cross between听T. latifolia听补苍诲听T. angustifolia. It was originally thought to be sterile, but thorough genetic studies have shown that听T. x glauca听can mate with other hybrids and with either parent, though it produces fewer seeds than other species. Where broadleaf, narrowleaf and hybrid cattails grow together, hybrid cattails frequently become dominant, suggesting an advantage in asexual reproduction.

Broadleaf cattails can be separated from the other species by the form of their flower stalks. The stalk has both male flowers that release pollen and female flowers that produce seeds. In all species, the male flowers are in the upper portion of the stalk while female flowers are below. Broadleaf flower stalks have male and female flowers tightly abutting, while the other species have a distinct space of two to four centimeters where the stalk is naked.听

Male flowers mature first and when the pollen has been shed the upper portion of the flower stalk dries and snaps off in the wind, leaving the densely packed female flowers that suggested the common name "cat tail." This mass of flowers and developing seeds is brown in broadleaf, reddish brown in narrowleaf, bright cinnamon brown in southern and light tan in hybrids.

Hybrid cattails might occur wherever broadleaf and narrow leaf cattails occur together, but they can be absent, rare or even dominant. In a study of flowering time and seed set in a constructed wetland in Ohio, no hybrids were produced in six years.听

Hybrid cattails are common in the Midwest, so this result was unexpected and puzzling. A subsequent study of hybrid success discovered that broadleaf cattails can be locally adapted to high salinity, providing them with an advantage over hybrids in saline environments.听

Other studies have shown that competitive outcomes also vary with water depth. So, competitive abilities and resulting abundances of the species vary with local adaptation, salinity and water depth. Cattails are currently invasive in the Florida Everglades, around the Great Lakes and the Prairie Pothole Region in the upper Midwest, so biologists would like to predict where they will spread and which species will be involved. But the more we learn about the species and their environments, the more difficult it becomes to predict the outcome of competition and which species will invade.

Two observations of cattails seem robust. Invasive propensities of the various species are enhanced and more successful in eutrophic and disturbed environments. Consequently, both native and introduced cattails are expanding their ranges.听

Native Americans were fond of cattails, for they fashioned the leaves into baskets, harvested the fluffy seeds to make pillows, insulation and diapers, and they ate almost every part of the plants. The abundant pollen was added to flour to make pancakes and muffins. When the female flowers were developing, they could be pickled or cooked and eaten with butter. The inner portions of young shoots were eaten raw or cooked. The rhizomes were abundant sources of flour and starch.听

We live in different environments than the Native Americans, and consequently cattails can no longer be eaten with impunity. Cattails, particularly broadleaf cattails, extract heavy metals from the water and concentrate them in their tissues, making them useful as bioindicators of pollution by manganese, zinc, cadmium, lead, nickel, copper and cobalt.听

Harvesting tasty food from wild plants sounds appealing, but inadvertently eating food liberally seasoned with heavy metals would be regrettable.