182 ERYTHEA. 
nearest ally, demeans itself like L. Menziesii; and there is 
but one other that ever becomes a wayside weed. That is L. 
nitidum, the most generally disseminated of all the species, 
making itself at home in almost all kinds of soil except the 
low and subsaline places, showing no preference for waysides 
though often growing there, but never associating with L. 
Menziesii in those excessively hard-packed old roads and 
paths which that species exclusively affects. It is also 
entirely disassociated from the other native species, each one 
of which seems to require its own peculiar kind of soil, and. 
never to appear in any other. 
Neither roadside nor sandy plain nor gravelly hill nor roll- 
ing prairie ever furnishes a habitat for the coarse Lepidium 
latipes. It abounds on lowrich plains of the interior, seldom 
if ever appearing except where water stands upon the ground 
in broad pools during the early months of the year. DL. oxy- 
carpum is another which need not be sought save where the 
land is moist and subsaline; it may be about a mineral spring 
in the hill country, or it may be along the border of a sea- 
board salt marsh. It is even occasionally associated with L. 
latipes. The other two species that are native in middle Cal- 
ifornia are L. dictyotum and L. Oreganum. The first of these 
is seldom seen; and belongs only to low plains where the soil 
is very strongly alkaline. L. Oreganum, as far as known in 
California, likes a sandy and slightly alkaline soil. Though 
brought to light in the first place from Oregon, there is no 
doubt this species is native, perhaps all up and down the foot- 
hills of the inner Coast Range of California. 
Among West American composites there is one native 
species very widely dispersed which I have never yet found 
growing in virgin soil. I refer to Matricaria discoidea. No 
wayside weed is more common in California, and not even 
Mayweed, its Old World relative, is more strictly domestic in 
all its habits. Around buildings, along the paved streets of 
cities, fringing the most beaten paths of men and animals, 
and seldom anywhere but in the hardest, yellowest, and most 
impermeable soil, grows this small, innocuous, and even sweet- 
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