Fruit anatomical and micromorphological structures from 28 species of Heracleum and three species of Angelica as outgroups were examined under light microscopy to identify characters useful in delimiting clades circumscribed in a previous molecular phylogenetic study. Maximum parsimony analyses of 20 fruit structural characters resulted in a generally poorly resolved strict consensus tree, yet one whose major clades matched those revealed previously. Angelica apaensis and Heracleum xiaojinense are best treated as the single species Angelica apaensis within Angelica s. s. All remaining Heracleum species share a highly lignified hypendocarp and a lignified endocarp, vascular bundles in marginal wings situated in the middle of the wing, and a commissure width the same as the mericarp width. These Heracleum species are recognized in four major clades with the following fruit structural features: (1) Heracleum s. s., having non-septate, clavate dorsal vittae that do not extend to the bottom of the seed; (2) Candicans (Villosa) clade, having marginal wings approximately half thewidth of the fruit and small seeds; (3) Millefolia clade, having narrow marginal wings, long dorsal vittae, large seeds, and rib oil ducts; and (4) Tetrataenium s. s., having prominent dorsal ribs, very wide marginal wings, dorsal and commissural vittae of similar length, 3-4 commissural vittae, and very small seeds.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Plant Science