Burke: Centaurea melitensis vs. Centaurea calcitrapa

	Centaurea melitensis	Centaurea calcitrapa
	Maltese starthistle, tocalote	purple starthistle, red starthistle
Habit	Annual, 1.5-7 dm. tall, lightly covered with crisp hairs, the stem with narrow wings from the leaf bases.
Leaves	Basal and lower cauline leaves oblanceolate, toothed to lyrate-pinnatifid, 3-15 cm. long and 5-35 mm. wide, usually deciduous; middle and upper cauline leaves smaller, becoming linear-oblong and entire upward.
Flowers	Heads few to numerous; involucre 8-15 mm. high, broader toward the base, its middle and outer bracts spine-tipped, the central spine 5-9 mm. long; the inner bracts purple tinged; flowers yellow, all alike; pappus 1.5-3 mm. long; receptacle strongly bristly.

	Centaurea melitensis	Centaurea calcitrapa
Flowering time	June-September	July-September
Habitat	Roadsides, meadows, balds, fields, ditches, wastelots, and other disturbed, open areas at low to middle elevations.	Roadsides, fields, ditches, wastelots, and other disturbed, open areas.
Distribution	Occurring chiefly west of the Cascades in Washington; British Columbia to California and Mexico, east to Texas and eastern North America. [WildflowerSearch map] [BONAP county map]	Occurring east of the Cascades crest in Washington; Washington to California, east to New Mexico, also in eastern North America. [WildflowerSearch map] [BONAP county map]
Origin	Introduced from the Mediterranean region	Introduced
Conservation status	Not of concern	Not of concern
Sibling taxa	C. benedicta, C. calcitrapa, C. cyanus, C. diffusa, C. ×gerstlaueri, C. iberica, C. jacea, C. macrocephala, C. montana, C. nigra, C. nigrescens, C. solstitialis, C. stoebe, C. trichocephala, C. ×varnensis	C. benedicta, C. cyanus, C. diffusa, C. ×gerstlaueri, C. iberica, C. jacea, C. macrocephala, C. melitensis, C. montana, C. nigra, C. nigrescens, C. solstitialis, C. stoebe, C. trichocephala, C. ×varnensis
Web links	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Centaurea calcitrapa

Maltese starthistle, tocalote

purple starthistle, red starthistle

Habit

Annual, 1.5-7 dm. tall, lightly covered with crisp hairs, the stem with narrow wings from the leaf bases.

Leaves

Basal and lower cauline leaves oblanceolate, toothed to lyrate-pinnatifid, 3-15 cm. long and 5-35 mm. wide, usually deciduous; middle and upper cauline leaves smaller, becoming linear-oblong and entire upward.

Flowers

Heads few to numerous;

involucre 8-15 mm. high, broader toward the base, its middle and outer bracts spine-tipped, the central spine 5-9 mm. long; the inner bracts purple tinged;

flowers yellow, all alike;

pappus 1.5-3 mm. long;

receptacle strongly bristly.