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How does parietal placentation differ from axile placentation in Lamiales?
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Lamiales
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In the context of the Lamiales order, the primary difference between parietal and axile placentation lies in the location where the ovules develop within the ovary:
- Axile Placentation: The ovules develop on a central column located at the axis of the ovary. This is the most common form of placentation found among the families of the Lamiales order.1
- Parietal Placentation: The ovules are positioned along the inner walls of the ovary or along partial partitions that extend inward from the walls. While less common in the order than axile placentation, this arrangement is characteristic of certain families, such as Orobanchaceae and Gesneriaceae.1
These arrangements are determined by the configuration of the carpels within the compound pistil; in axile placentation, the carpels are folded inward toward the center, whereas in parietal placentation, the carpels are united by their adjacent margins.21