Although many methods have been adopted for the successful cultivation of the best species and varieties, failure has been the rule, so that at present few American collections contain even a single specimen. Plants introduced by collectors sometimes thrive for a few years and then fail, in spite of all efforts. Frequently they can be kept only a year or two. | Although many methods have been adopted for the successful cultivation of the best species and varieties, failure has been the rule, so that at present few American collections contain even a single specimen. Plants introduced by collectors sometimes thrive for a few years and then fail, in spite of all efforts. Frequently they can be kept only a year or two. |