. An illustrated flora of the northern United States, Canada and the British possessions : from Newfoundland to the parallel of the southern boundary of Virginia and from the Atlantic Ocean westward to the 102nd meridian. f the disk-flowers hispid, tipped with elongated appendages. Achenes thick, 4-sided, truncate at thesummit. Pappus none, or of several short scales. [Greek, 4-angled-case, referring to theinvolucre.] Four known species, natives of the southern United States and northern Mexico, the follow-ing typical. I. Tetragonotheca helianthoides Fig. 4440. Tetragonotheca
. An illustrated flora of the northern United States, Canada and the British possessions : from Newfoundland to the parallel of the southern boundary of Virginia and from the Atlantic Ocean westward to the 102nd meridian. f the disk-flowers hispid, tipped with elongated appendages. Achenes thick, 4-sided, truncate at thesummit. Pappus none, or of several short scales. [Greek, 4-angled-case, referring to theinvolucre.] Four known species, natives of the southern United States and northern Mexico, the follow-ing typical. I. Tetragonotheca helianthoides Fig. 4440. Tetragonotheca helianthoides L. Sp. PI. 903. 1753. Viscidly pubescent; stem brancned or sim-ple, i°-2i° high Leaves ovate, ovate-oblong,or somewhat rhomboid, thin, coarsely and un-equally dentate, pinnately veined, acute at theapex, narrowed at the sessile or somewhatclasping base, 2-6 long, i-3 wide; headsusually few, i¥-2, broad; involucre 4-angledin the bud, its principal bracts broadly ovate,acute; rays 6-10, strongly parallel-nerved, 2-3-toothed; corolla-tube villous below; achenes4-sided, or nearly terete; pappus none. In dry soil, Virginia to Tennessee, Florida andAlabama. May-June. Sometimes flowering againin Genus 6o. THISTLE FAMILY. 469 60. SPILANTHES Jacq. Stirp. Am. 214. pi. 126. 1763. Annual or perennial branching herbs, with opposite, usually toothed leaves and rathersmall, long-peduncled discoid and radiate heads, terminal, or in the upper axils, or rayswanting in some species. Involucre campanulate, its bracts in about 2 series, herbaceous,loosely appressed. Receptacle convex or elongated, chaffy, its chaff embracing the disk-achenes and at length falling away with them. Ray-flowers yellow, or white, pistillate, some-times wanting. Disk-flowers yellow, perfect, their corollas tubular with an expanded 4-5-cleftlimb. Anthers truncate at the base. Style-branches of the disk-flowers long, sometimespenicillate at the summit. Ray-achenes 3-sided, or compressed, those of
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1913
