polycarpon

from The Century Dictionary.

• noun A genus of diffuse polypetalous herbs of the order Caryophylleæ, type of the tribe Polycarpeæ and characterized by the five keeled and entire sepals, the five small entire hyaline petals, the three to five stamens, and the one-celled ovary with many ovules, crowned with a short threecleft style, and becoming a small three-valved capsule.