Uncommon branching pattern within conifers: Frenelopsis turolensis, a Spanish Early Cretaceous Cheirolepidiaceae

Abstract

The fossil plant Frenelopsis turolensis Gomez from the Lower to Middle Albian of the Escucha Formation (Iberian Ranges, Spain) displays a combination of leaf and branch arrangements unknown in extant conifers. Detailed architectural analyses allow for elucidation of the branching pattern of this species. Branching occurs above a leaf of the whorl but at some distance from the node, within the internodal region. This event may be the result of adnation or hypomerithallus formation. We point out a new type of branching pattern for Frenelopsis based on F. turolensis, with no discontinuity in the leaf sequence. This unusual ontogeny of the branches asserts that branching is more diverse in the fossil cheirolepidiaceous genus Frenelopsis than previously supposed.Key words: branching pattern, ontogeny, Cheirolepidiaceae, Frenelopsis, Cretaceous, Spain.