Consequently, the Ovule can derive nutrition from the sporophyte during all stages of its development. If you reflect on Selaginella , you may recall that the Megaspores lie inside the Megasporangium which does not have a vascular connection with the Sporphyte. Megaspores are released before they are mature and complete their development in nature. Imagine that the Megasporophyll gradually enveloped the Megasporangium so that it was enclosed except for an opening at its tip. This would be similar to an Ovule.
Gymnosperms are Heterosporous .
The Megasporangia and Microsporangia are organized into Cones . Plants are either Male or Female . The foliar nature of the Megasporophyll is fairly obvious for ancestral Cycads that belong to the genus Cycas . Model of Formation of an Ovule from a Megasporophyll similar to Selaginella . Further marginal curving.