Definition: Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.
Input: Wahlenbergia species have dispersed widely, even to oceanic islands, and there are four species known from the island of St Helena, including the now extinct species W. roxburghii.

Wahlenbergia species have spread out widely, even to oceanic islands. There are four species known from the island of St Helena. That includes the now extinct species W. roxburghii.