WEEDS OF MONTANA. 11 



1 . It is most abundant at the supposed point of introduction, 

 decreases in numbers departing therefrom and is wholly absent in 

 distant or isolated localities. 



2. It does not occur in isolated localities growing wild under 

 natural conditions and forming an integral part of the indigenous 

 flora, or is known to be a recent introduction into such localities. 



3. It is sporadic in localities widely separated and is much more 

 abundant or occurs in greater perfection in another region from 

 which its introduction may be inferred through known agencies. 



4. It is normally found occupying localities in which the 

 native vegetation has been weakened or destroyed by the presence 

 of man and his domestic animals and is rare or lacking in the 

 county adjacent. 



The source of its introduction is (1) from a region of its known 

 occurrence adjacent or remote, or (2) from the direction of its 

 greatest abundance in the state, or (3) from the usual source of 

 seed importation into the state, or of travel through it. 



Judged by these criteria, the following species may be con- 

 sidered indigenous, although a number (here starred *) by their 

 present restricted distribution in the state and the fact that their 

 bounds are being still extended, indicate that they are of compara- 

 tively recent introduction and may best be termed "submdigenes," 

 while a few (f) are doubtful. 



I. ANNUALS. 



*Amaranthus albus, L. *Helianthus annuus, L. 



*A. blitoides, Wats. IH. petiolaris, Nutt. 



*Chenopodium glaucum, L. ilva xanthiifolia, Nutt. 



*Cleome integrifolia, T. & G. *Krinitzkia crassisepala, Gray. 



Draba nemososa, L. *Lepidium apetalum, Wild. 



*Dracocephalum parviflorum, Nutt. vMonolepis chenopodioides, Moq. 



*Echinospermum Redowskii, Lehm. *Plantago Pata^onica, Jacq. 



*Euphorbia glyptosperma, EngsLn. tSisymbrium incisum, Engelm. 



*Franseria Hookeriana, Nutt 'Solanum triflorum, Nutt. 

 *Ellisia Nyctelea, L. 



II. BIENNIALS. 



Cnicus eriocephalus, Gray. 'Hordeum jubatum, L. 



*Gaura parviflora. Dougl. tOenothera biennis, L. 



•Grindelia squarrosa, Dunal. 



