For instance, the blue and red pimpernel, which are considered by most botanists as varieties, are said by Gartner to be quite sterile when crossed, and he consequently ranks them as undoubted species.

例如，数植物学家认为是变种的色和红色 pimpernel，Gartner 认为杂交后非常， 此他将它们列为无可置疑的物种。