Phylogenetic Analysis of Lappula Moench (Boraginaceae) Based on Molecular and Morphological Data

Lappula Moench (Boraginaceae), a genus comprising ca. 70 species, has a cosmopolitan distribution, with species in Eurasia, Africa, North America, and Australia. Although the genus has a wide geographic distribution, its center of diversity is in Central Asia. Lappula is characterized by prickly cauline leaves, blue corollas that each bear five prominent appendages at the apex of the corolla tube, a subulate gynobase, and nutlets with either marginal anchor-like spines or marginal wings tipped with anchor-like spines.

Despite all the taxonomic and morphological studies of Lappula, phylogenetic studies are lacking. Only a few studies have investigated the phylogenetics of Lappula, with most including only one or two species of the genus. Consequently, the phylogenetic position of Lappula as well as the infrageneric relationships are not well understood.

To elucidate phylogenetic relationships and morphological evolution within Lappula and related genera, four DNA regions—the nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) and three chloroplast DNA (cpDNA) regions (trnL-trnF, rpS16 and psbA-trnH)—were sequenced, and 18 morphological characters were investigated. Combining molecular and morphological data, HUANG Jianfeng et al. examined phylogenetic relationships within Lappula and among related genera as well as assessed the evolutionary patterns of morphological characters within the genus.

Phylogenetic results suggest that the current infrageneric classification of Lappula, at least at the subsectional and series level, is artificial. The evolutionary patterns of 18 morphological characters are investigated in a phylogenetic context. In Lappula, nutlet homomorphism and small corollas are resolved as ancestral, while nutlet heteromorphism and larger corollas are derived. The result was published in Plant Systematics and Evolution, 2013, 299(5): 913-926.