What is the fine-grained topic of the following text: Species popular in collections include: P. armeniacum,, P. barbatum, P. callosum, P. charlesworthii, P. concolor, P. delenatii, P. farrieanum, P. lowii, P. malipoensis, P. micranthum, P. rothschildianum, P. sanderianum P. sukhakulii and a long etc. Only return the topic.
Popular species in plant collections