Thursday, October 27, 2011

Ethnobotany for Green Roofs, Achillea millefolium, Yarrow on Florida Green Roofs

Rooftop ethnobotany should be a part of all green and living roofs as plants have given humans food, fiber and medicine throughout the ages.

One of my favorite green roof plants rich in ethnobotanical history is Yarrow.

Green Roof Achillea millefolium, ethnobotanical wonder and living roof beauty

Yarrow is a hardy Northern Hemisphere native wildflower suited for hot, dry green roofs. Yarrow is found growing as a native plant around the world in the northern hemisphere. 

Her Mexican name is plumajilla or ‘little feather’ due to the feathery shape of her leaf.
Important to biodiversity support, many birds (including sparrows) use the soft leaves of the plant to line their nest.  The leaves are quite soft and add a blanket of light green color across the green roof for much of the spring and early summer.  When the blooms began to appear during late May and June the plant sends up shoots, supporting beautiful umbells of flowers. 
Green Roof Achillea millefolium, Breaking Ground Green Roof
Yarrow has a rich ethnobotanical history having been used for centuries as a wound herb, and is famous for the capability to stop bleeding from cuts. The leaves may be used as a spinach like vegetable, cooked or in salads.  The plants has also been used as a flavoring in beer. Yarrow has EO data suggestion insecticidal qualities against common mosquitoes.

MetroVerde Green Roofs supporting biodiversity on many levels, Yarrow

Yarrow can tolerate hot, dry soils with little organic material.  A member of the Asteraceae family the plant is very drought tolerant once established. The flowers add a variety of surprisingly bright color to the green roof as many other flowering plants are seeding out and loosing their color.  The perennial plant usually comes back and flowers reliably, year after year.

During the harvest season when most green roof plants are beginning to wear a tired look from summer's heat and humidity, Yarrow is just beginning to develop a rich, deep rainforest-like green hue.

Shown growing here with Pennywort, Hydrocotyle spp. and Aloe, Yarrow serves as a weed blocking  groundcover worthy of any living roof.

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