The Yarrows – horticultural plants extraordinaire Family: Asteraceae (Sunflower family) Cultivated in Europe ??thousands of years About half a dozen species are commonly grown as garden plants Natural variation in color has been exploited – many named cultivars – yellow, pink, red, purple The species name, millefolium-of a thousand leaves-describes the fine, feathery foliage which resembles a fern. http://aggiehorticulture.tamu.edu/ornamentals/Cornell_Herbaceous /plant_pages/Achilleamillefolium.html
Western Yarrow – Achilla millefolia Found in most of CA 60-100 species of Achillia worldwide – northern hemisphere In CA, found in seasonally wet places:http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?609,615,616 Meadows and pastures Along stream edges In sand dunes Along alkali sinks On coastal strand In coastal grasslands In Coastal Sage Scrub and Chaparralhttp://linnaeus.nrm.se/flora/di/astera/achil/achimilv.jpg
Western Yarrow can be used in many ways! Slopes, hillsides Mixtures Good garden plant for fresh or dry floral arrangements Foliage is pleasantly fragrant when crushed – used for tea, medicinals Can be mowed to form a highly competitive ground cover to control soil erosion. Flowers!!! Good butterfly/insect plant J.S. Peterson @ USDA-NRCS PLANTS Database
Success with Yarrow is almost guaranteed Yarrow can endure dry, impoverished soil Survives with little maintenance – neglect Best in full sun; grows but less flowering in shade A true perennial taking two years to become established Included in most commercial mixed ‘native lawn’ mixesGary A. Monroe @ USDA-NRCS PLANTS Database
Why Yarrow makes a good lawn substitute Spreads quickly, giving good cover Super for banks and other areas that can’t easily be mowed Spreading habit inhibits weeds Can be mowed – occasionally and on high setting w/ rotary mower Companion plant – attracts beneficial insects, repels others Does well on poor, dry, sandy soils where other plants grow poorly http://www.dgsgardening.btinternet.co.uk/yarrow.JPG
Potential Risks/Controversies: Human Health Effects Introducing allergens and toxins into food Transfer of antibiotic resistance marker genes; cause the development of diseases which are immune to antibiotics Unknown effects of a new – and biologically basic – technology; not much is known about their long- term effects on human beings
Potential Risks: Environmental Effects Unintended phytotoxicity: plants less resistant to other pathogens/environmental challenges Adversely changing the nutrient content of a crop; consequences for herbivores Antibiotic resistance is spread: to other (wild) plants, animals, microorganisms Emergence of "super" weeds: herbicide/pest resistant; high yield Development of (or, more rapid development of) insecticide resistance in pests
Potential Risks: may worsen current environmental challenges Unintended transfer of transgenes through cross- pollination Unknown effects on other organisms (e.g., soil microbes; butterflies); toxicity Loss of floral and faunal biodiversity: farmers plant only the GM plants; beneficial insects killed Effects of global climate changes – changed geographic distribution of pests; ?? Impact of transgenic plants; pollinator diversity, etc.