Embryo and endosperm development in Billbergia nutans H. Wendl. ex Regel (Bromelioideae - Bromeliaceae) and its implications for the embryonomy of Bromeliaceae

•Billbergia nutans follows the Onagrad Type of embryogenic development•The Onagrad Type of embryogenic development is unprecedented for Bromeliaceae•A new variation for this type is proposed: Billbergia Variation•Billbergia Variation can be applicable to some other bromeliads•Cellularization in the helobial endosperm occurs at specific embryogenic stages.