An organismal concept for Sengelia radicans gen. et sp nov - morphology and natural history of an Early Devonian lycophyte

作者：Matsunaga Kelly K S^*; Tomescu Alexandru M F

来源：Annals of Botany, 2017, 119(7): 1097-1113.

DOI：10.1093/aob/mcw277

• Lycopsida
• Devonian
• evolution
• morphology
• fossil
• Sengelia
• Drepanophycus
• organismal concept
• natural history
• microconchid

Background and Aims Fossil plants are found as fragmentary remains and understanding them as natural species requires assembly of whole-organism concepts that integrate different plant parts. Such concepts are essential for incorporating fossils in hypotheses of plant evolution and phylogeny. Plants of the Early Devonian are crucial to reconstructing the initial radiation of tracheophytes, yet few are understood as whole organisms.
Methods This study assembles a whole-plant concept for the Early Devonian lycophyte Sengelia radicans gen. et sp. nov., based on morphometric data and taphonomic observations from >1000 specimens collected in the Beartooth Butte Formation (Wyoming, USA).
Key Results Sengelia radicans occupies a key position between stem-group and derived lycophyte lineages. Sengelia had a rooting system of downward-growing root-bearing stems, formed dense monotypic mats of prostrate shoots in areas that experienced periodic flooding, and was characterized by a life-history strategy adapted for survival after floods, dominated by clonality, and featuring infrequent sexual reproduction.
Conclusions Sengelia radicans is the oldest among the very few early tracheophytes for which a detailed, rigorous whole-plant concept integrates morphology, growth habit, life history and growth environment. This plant adds to the diversity of body plans documented among lycophytes and may help elucidate patterns of morphological evolution in the clade.

• 出版日期2017-5