434 



EXOGENOUS OR DICOTYLEDONOUS PLANTS. 



cies of Artemisia) ; sometimes accompanied by acrid qualities, as 

 in the Tansy (Tanacetum vulgare), and the Mayweed (Maruta 

 Cotula), the bruised fresh herbage of which blisters the skin. The 

 species of Liatris, which abound in terebinthine juice, are among 

 the reputed remedies for the bites of serpents. The juice of Sil- 

 phium and of some Sunflowers is resinous. The leaves of Soli- 

 dago odora, which owe their pleasant anisate fragrance to a pe- 

 culiar volatile oil, are infused as a substitute for tea. From the 

 seeds of Sunflower, and several other plants of the order, a bland 



771 772 773 780 781 



oil is expressed. The tubers of Helianthus tuberosus are eaten 



FIG. 771. Head of Liatris squarrosa (discoid; the flowers all tubular and perfect). 772. The 

 same, with the scales of one side of the imbricated involucre removed ; and also all the flowers 

 but one, showing the naked flat receptacle. 773. Portion of one of the plumose bristles of the 

 capillary pappus. 774. Head of Helenium autumnale (heterogamous) ; the rays neutral, con- 

 sisting merely of a ligulate corolla. 775. The same, with the flowers all removed from the 

 roundish receptacle, except a single disk-flower and one or two rays : the reflexed scales of the 

 involucre in a single series. 776. Magnified disk-flower of the same ; the corolla exhibiting the 

 peculiar venation of the family; namely, the veins corresponding to the sinuses, and sending a 

 branch along the margins of the lobes. 777. The same with the corolla removed ; the achenium 

 crowned with the limb of the calyx in the form of a chaffy pappus, of about five scales. 778. A 

 chaff of the pappus more magnified. 779. A tubular corolla of this family laid open, showing 

 the venation ; and also the five syngenesious anthers united in a tube, through which the two- 

 cleft style passes. 780. Head of Dracopis amplexicaulis, with the flowers removed from the 

 elongated spike-like receptacle, except a few at the base : a, achenium of one of the disk-flow- 

 ers, magnified, partly inclosed by its bractlet (chaff or palea) ; the pappus obsolete. 781. Part 

 of the involucre and alveolate (honeycomb-like) receptacle of Onopordon or Cotton-Thistle. 

 782. A perfect and ligulate flower of the Dandelion, with its hair-like or capillary pappus. 



