Petrosaviaceae

Petrosavia sakuraii

The Petrosaviaceae are a plant family with three species in two genera, and the only family of the order of Petrosaviales.

Description

There are perennial herbaceous plants with slender and scaly rhizomes. The stem is erect, unbranched and thin, the leaves are spirally arranged. The species of the genus Petrosavia are mykoheterotrophe plants.

The terminal inflorescence is a panicle or cluster of more than ten flowers. The upright, hermaphroditic and single -stemmed flowers arise from the axils of small bracts, which often contrasts with a bract. The six bracts are fused at the base of the inner petal circle are greater than that of the outer. The stamens of the six stamens are commended shaped and fused with the approach of the bloom, the anthers ovate and turned inwards; the pollen monosulcat. The three pens are short. The ovary is upper constant to medium ever, there are follicles formed. The seeds are elliptical and between 0.3 and 0.8 millimeters long.

Distribution area

The species of the order are from China and Japan over parts of Southeast Asia (Malaysia, Myanmar, Thailand, Vietnam) to Indonesia (Borneo ) spread. You will find yourself there in mountainous areas 1000-1600 meters.

System

All taxa of the order have a checkered past and were often rearranged. The species of the order share relatively few morphological features to each other, which were but due to their rarity in the Liliidae and in their combination seen as sufficient to support the molecular genetic relationship determined. According to Cameron et al. 2003 currently includes the following order types:

• Japonolirion Nakai: The only kind: Japonolirion osense Nakai

• Petrosavia Becc. ( Syn: Miyoshia Makino, Protolirion Ridley ): With only two types: Petrosavia sakuraii ( Makino ) JJSmith ex van Steenis
• Petrosavia stellaris ( K.Krause ) Gagnepain

At the same time the genera Protolirion and Miyoshia went on in the genus Petrosavia.

Japonolirion was once mostly provided to the Melanthiaceae, but occasionally also treated as a separate family Japonoliriaceae. The rank of the family, however, is Petrosaviaceae since 1934 largely uncontroversial, strong uncertainty prevailed, however, with regard to the placement of the family, she was assigned to both the Alismatales, Triuridales as Miyoshiales, only in 1997 the family was granted by Takhtajan the rank of a private order. This classification was confirmed by subsequent molecular genetic studies.

With an age that, with around 123 million years ( Crown node age) is specified, the Petrosaviaceae the oldest extant family of monocots are probably ever.