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WEEDS OF MAINE. 255 



A pretty little native, frequently very abundant in dry sterile 

 fields and by the roadsides. In May we have seen barren fields 

 literally white with the small but showy flowers of the Houstonia. 

 It generally forms patches of greater or less extent. Good culti- 

 vation will soon eradicate it. 



Order 18. COMPOSITES. — SUN-FLOWERS. — ASTER- 

 WORTS — CoMPOSiTiE. A brief description of this truly Royal 

 Family of plants will greatly abridge the specific descriptions. 



Mostly herbs. Leaves never truly compound. Flowers few to many, crowded on a coni- 

 ponnd receptacle, into a close head, surrounded by numerous leaflets or scales, forming 

 an involucre. The separate flowers are often furnished with bracelets {chaff or paleas). 

 The limb or border of the calyx is divided into bristles, hairs, or scales {pappus). The 

 Corolla is either tubular and five lobed or strap-shapeJ and five toothed. 



This vast family comprises about a tenth part of all flowering 

 plants ; numbering about one thousand genera and nine thousand 

 species. The whole family may be known at a glance by their 

 capitate (arranged in heads) flowers and united anthers. The 

 flowers are either polygamous, monoecious, dioecious, or all perfect. 

 The plants of this family are diffused throughout the world. 

 According to Humboldt, they constitute about one-seventh of the 

 flowering plants of Germany ; one-eighth of France ; one-fifteenth 

 of Lapland; one-sixth of North America (north of Mexico); and 

 one-half of Tropical America. All the composite plants of the 

 temperate regions are herbaceous, while towards the tropics they 

 gradually become shrubs and even trees. "A bitter astringent 

 principle pervades the whole order; which in some species is tonic, 

 as in Chamomile, the Boneset or Thoroughworl; in others combined 

 with mucilage, so that they are demulcent as well as tonic, viz : 

 Elecampane {Inula ffelenium) and Colt' s-foot (Tussilago Fa7'fara); 

 in others aromatic and extremely bitter (as Wormwood and all 

 species of ^r/emma); sometimes accompanied by acrid qualities 

 {Tansy and May-weed), the bruised fresh herbage of which blisters 

 the skin. The species of Liatris (Button Snakeroot or Blazing- 

 Star), which abound in terebinthine juice, are among the reputed 

 remedies for the bites of serpents ; so are some species of llikania 

 in Central America. The juice of Silphium and of some sunflowers 

 is resinous. The leaves of Solidago odora, which owe their pleas- 

 ant anisate fragrance to a peculiar volatile oil, are infused as a 

 substitute for tea. From the seeds of sunflower, and several other 

 plants of the order, a bland oil is expressed. The tubers of Heli- 



