592 : General Notes. ` [Angust 
more vigorous organization, by superseding the weaker ones, 
would have produced originally the monotony developed at pres- 
ent by the immigration of foreign plants. 
First of all I mention Szybum marianum, a native of the Med- 
iterranean region, observed by me the first time in 1854 in Cali- 
fornia, in 1848 in South Australia. Wherever it gets a hold of 
the soil all native vegetation disappears. (California is not the 
only land invested by this thistle. I have witnessed the same 
invasion in South Australia, and have read the statement of my 
former teacher, Prof. Burmeister, at present in Buenos Ayres, that 
the same thistle protects, through the time of its vegetation, the 
settlers against inroads of the Pampas Indians, as even these wild 
horsemen cannot cross the immense thickets formed by the same 
species of thistle. The influence of this weed is not confined to 
the neighborhood of San Francisco, and it is chiefly the miniature 
forests of lupines that suffer from its invasion. i 
Another weed, Cotula coronopifolia, does the same work in 
moist ground that is begun by Silybum in the more arid tracts of 
soil. The plant, a native of Southern Africa, was observed for 
the first time by me in 1854. I also have witnessed its invasion 
of South Australia, and I recollect very wèll the single specimen 
I found near Adelaide in 1845. It is well known in Mediterranean 
Europe, but as to the date of'its invasion, I only know that it 
was common there at the same time when I found the first speci- 
men in Australia. This weed has transformed the varied aquatic 
vegetation of the different places invested by itself into one 
monotonous green mass with yellow buttons, Our graceful water 
fern, Azolla, that formerly ornamented abundantly our creeks by 
its floating turf, is scarcely to be found any more. a 
Now, both of these plants which could be called “ the coming 
plants,” are Syngenesists or Composit. The Composite themselves 
are characteristic of the most modern flora, for in a fossilized state 
they are only found in the most modern formations ; in fact, the 
only fossilized Composite of which I know, were products of a 
river that fossilized everything thrown into it. Now it appears 
that in the fight for existence the junior sons of creation have a 
decided advantage, and this accounts for the otherwise inexplica- 
ble circumstance that the variety of organisms decreases so per~ 
ceptibly when we enter the realms of Gymnosperms, vascular 
Cryptogams, and all those forms of organic life that existed in the 
early periods of the earth. 
Boranicat Notes,—In the Buletin of the Torrey Botanical 
Club, which, by the way, now appears regularly each month, and 
with a neat cover, Mr. G. E. Davenport describes and figures 1n 
an excellent plate, a new fern (Notholena grayi) from Southeastern 
Arizona. Grevillea for June contains a thoughtful essay oa 
Peziza, by M. C. Cooke. The Journal of Botany for May and 
June continues to review the British Characeæ, and the bot- 
