Earth Notes: Winter's Evergreens

Tristan Clum — Wed, 28 Dec 2011 07:00:00 +0000

When summer’s flashy circus of wildflowers has passed and the last browned autumn leaf has fallen, an eye looking for signs of plant life is left with the conifers, those stalwart trees that stay green all year long.

Conifers do drop their needles and replace them with new ones—just not all at once. Their ability to photosynthesize all year long gives them a built-in advantage in living in places with a relatively short warm season. So does their natural chemical antifreeze, which prevents needles from freezing even in frigid conditions.

Earth Notes: Controlling a Weed—With a Bug

Tristan Clum — Wed, 16 Nov 2011 16:29:31 +0000

When it comes to controlling the many non-native, invasive plants in northern Arizona, weed warriors call on every tactic in the book. As they seek to minimize the spread of a weed called diffuse knapweed, they’re turning to a tiny ally: a weevil that loves to eat knapweed seeds.

Diffuse knapweed is a low-growing shrub that originated on the Russian steppes. Since the 1980's, it’s taken over roadsides and pastures in the region. It’s a heavy seed producer and a tough competitor against native plants.