Flora and fauna of the Athens County area, and occasionally habitats outside Ohio. Subject matter will consist of both interpretive material and taxonomic issues in plant and animal identification.
Friday, September 17, 2010
Thistles do not tickle
1a) Main stem covered with prickly spines, either growing directly out of the stem, or on leaf-like wings. (All spiny species are non-native)...2
1b) Main stem, for the most part, without prickly spines...3
2a) Flower head large, several inches in diameter. Phyllaries (bracts) broadly shaped and sharp. Flower usually bent or nodding...Nodding Thistle, Carduus nutans
2b) Flower head smaller than above, bloom growing erect, bracts thin, sharp but needle-like...Bull Thistle, Cirsium vulgare
3a) Most leaves moderately lobed or completely unlobed...4
3b) Most leaves deeply lobed, dissected, or divided...5
4a) Plant 2-3 foot tall, flower heads numerous but small, one inch or less across...Canada Thistle, Cirsium arvense
4b) Plant 3-10 feet tall, flowers over one inch, leaves pale beneath...Tall Thistle, Cirsium altissimum
5a) Plant 2-3 ft. tall, flower heads 1" or less, plant often in clumps...Canada Thistle. (pictured above) So why did I put it in the key again? Because often portions of the plant have divided leaves.
5b) Plants 3-8 feet tall, flowers over one inch, leaves white wooly beneath...6
6a) Upper leaves surround flower head, protruding spines obvious on flower head, common in disturbed sites... Field Thistle, Cirsium discolor
6b) Few to no leaves around flower head, protruding spines absent, flower head covered in spider web like fuzz, stems hollow, common in wetlands...Swamp Thistle, Cirsium muticum