Minnesota Plant Life. 



369 



united into a tube, sessile flowers, fringed corolla scales and 

 obtuse calyx lobes, the stems pale yellow and thread-like, with 

 the flowers in little clusters ; the smartweed dodder, most abun- 

 dant on smartweeds, similar to the field dodder, but with the 

 thread-like stems of an orange-yellow color and the calyx lobes 

 acute; Choisy's dodder, developing stemmed flowers with dis- 

 tinct corollas, the lobes of which are curved in over the capsule ; 

 the hazel dodder, growing mostly upon hazel bushes, with cap- 

 sules capped by the shriveling corolla ; the button-bush dodder, 

 with corolla lobes spreading, not curved over the capsules, and 

 the capsule flattened and globular in form ; and Gronovius' 

 dodder, found, like the button-bush dodder, on a variety of 

 herbs and shrubs, but with pointed capsules. In all these dod- 

 ders the flowers are in rather loose clusters, when compared 

 with the remaining variety, known as the massive dodder. In 

 this species, occurring mostly on goldenrods, asters, sunflowers 

 and other herbs of the composite family, the flowers are borne 

 in very large numbers and very close together, quite concealing 

 the stem. The little dodder flower-clusters, therefore, give the 

 appearance of a coil of rope, turned three or four times around 

 the axis of the host-plant. 



The stems of all the dodders have sucking organs which 

 are driven through the skins of their host-plants and expose 

 their surfaces in the soft tissues. Through them the juices of 

 the host-plant are absorbed for the benefit of the dodder. This 

 kind of parasitism is derived from the habit of twining orig- 

 inated by those prototypes of the dodders, the morning-glories. 

 It is interesting to notice just how the parasitic habit probably 

 arose in this instance, because, in others, parasitism began in 

 quite different ways. 



Phloxes. The phlox family includes the Greek valerians, 

 phloxes, Gilias and Collomias. In all the Minnesota varieties 

 the flowers are tubular, with the lobes of the corolla spreading. 

 The fruit-rudiments are three-chambered, maturing into three- 

 chambered capsules. Four sorts of phlox occur in Minnesota: 

 The wild sweet-william, the downy, the blue, and the smooth 

 phlox. They are distinguished by the shapes and textures of 

 their leaves and by the colors of the flowers. 

 25 



