You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "In between Oxydendrum and Polygonum which one has  about 220 species?" whose answer is Polygonum.
Each document should contain about 30 words, and these documents should contain useful information.

Query: number of species Oxydendrum
Useful Output:

Doc 1: Oxydendrum arboreum, better known as the sourwood or sorrel tree, is the only species in its genus. It's native to eastern North America.
Doc 2: Sourwood, (species Oxydendrum arboreum), deciduous ornamental tree, of the heath family (Ericaceae), native to southeastern North America.
Doc 3: Characteristics: Just one species exists, Oxydendrum arboreum. Flowers are  Phone: 503.231.5050 5050 SE Stark, Portland, OR 97215. Portland Nursery
Doc 4: This is the only ericaceous species in the Southeast that is clearly a tree. The species is deciduous, of somewhat small to medium size, growing to about 40-50
Doc 5: This species has been reported in the following counties by the herbaria listed. An overview of the individual specimens are provided in the table that follows.