Di Schulz presented the Species Talk on 20 April 2013.
The following was taken from a Begonian of 1968.
The stems and branches of B. parilis are soft and hairy. Its leaves are velvet-like in texture, olive-green, red at the margins and red flushed beneath. Flowers are pink or white.
From Know Your Begonias by J Krempin.
B. parilis was discovered in Brazil in 1953. It is known as the zig-zag begonia. It is thick-stemmed, grows to 1 metre with zig-zagged branches and medium, narrow, shining green leaves, red beneath. Arching clusters of white flowers with yellow stamens appear in summer.
Begonias: The Complete Reference Guide by Thompson & Thompson has this to say.
B. parilis is a versatile begonia that is attractive whether it is staked or not. Although this plant branches naturally, early pinching will produce an even fuller plant. It can be grown effectively in maximum sunlight according to the locale, or it can be grown in a semi-shady position, making an interesting foliage plant. However, it will only bloom when there is sufficient sunlight.