From capsules to nutlets-phylogenetic relationships in the Boraginales.

Area of Science:

• Plant Systematics
• Molecular Phylogenetics
• Evolutionary Botany

Background:

• The order Boraginales has historically featured proposed family-level subdivisions with unresolved relationships for key genera.
• Genera such as Codon, Hoplestigma, Pholisma, Vahlia, and Wellstedia presented phylogenetic challenges within Boraginales.

Purpose of the Study:

• To resolve the phylogenetic relationships of enigmatic genera within Boraginales using molecular data.
• To establish a well-supported classification for the Boraginales order based on comprehensive phylogenetic analysis.

Main Methods:

• Conducted a molecular phylogenetic analysis utilizing four chloroplast loci.
• Included 89 ingroup taxa and a broad outgroup sampling within the asterids.
• Applied phylogenetic methods to reconstruct evolutionary relationships.

Main Results:

• The genus Vahlia was excluded from Boraginales, identified as an early lineage of Lamiales.
• Two major clades within Boraginales were resolved: "herbaceous" Boraginales I ([Codonaceae,[Wellstediaceae,[Boraginaceae]]]) and "woody" Boraginales II ([Hydrophyllaceae I,[Hydrophyllaceae II,[Heliotropiaceae,[Cordiaceae,[Ehretiaceae,Lennoaceae]]]]).
• Morphological progressions in fruit and seed characteristics were observed correlating with phylogenetic clades.

Conclusions:

• The study advocates for the recognition of eight morphologically distinct clades within Boraginales.
• Established a robust phylogenetic framework for Boraginales, clarifying the placement of previously enigmatic genera.
• Highlighted evolutionary trends in fruit and seed morphology across Boraginales lineages.