Explanation

The ovule in which the funicle, chalaza and micropyle lie on the vertical place is called orthotropous (Gk. Orthos = straight; tope = turned). In this type, the body of ovule is straight. Hilum and chalaza occur nearly. It is also called atropous or erect ovule, e.g., piperaceae, polygoniaceae, Urticaceae, etc. It is the most primitive and simplest type of ovule in angiosperms.