How did extinct Hyeniales plants differ from other sphenophytes?

The extinct Hyeniales differed from other sphenophytes primarily in their physical structure and reproductive organization. While many sphenophytes are characterized by distinct, regular whorls of leaves, the Hyeniales were shrublike plants that possessed inconspicuous leaves arranged in rather indistinct whorls.1

Furthermore, their reproductive structures, known as strobili or cones, lacked the sterile bracts—much-reduced leaves—that were associated with the strobili of other extinct groups such as the Sphenophyllales and the Calamitaceae. In this regard, the Hyeniales shared a similar reproductive feature with the Equisetaceae, as both groups lacked these associated sterile bracts.1