The subfamily Spiraeoideae traditionally comprises approximately 20 genera distributed
from South America north into Central and North America and Eurasia. Recent Rosaceae
classification based on molecular phylogeny define a broader Spiraeoideae subfamily
which includes the Maloideae as well as Amygdaloideae. The present study focuses
on the pollen morphology and leaf micromorphology include three tribes Spiraeeae,
Neillieae, Sorbarieae, which belong to the subfamily Spiraeoideae. In particular,
anatomical and molecular phylogenetic studies in tribe Sorbarieae are also conducted.
The main objects of this study are (1) to document and explore taxonomic, systematic
significant characters based on pollen and orbicule morphology, leaf, fruit and seed
micromorphology, leaf and petiole anatomy, (2) to reconstruct the phylogenetic
relationships among the genera and species of tribe Sorbarieae using nrDNA ITS and
cpDNA trn L-F sequences, (3) to provide a complete monograph of genus Sorbaria
based on morphology, palynology, micromorphology, and phylogeny. Variation in sexine
ornamentation of pollen may have systematic importance in Spiraeoideae particularly
at generic level. Moreover, our case study in three tribes indicate that orbicule existence
in Rosaceae is promising available taxonomic characteristic.
The diversity and taxonomic significance of the leaf micromorphological characteristics
such as stomatal complexes, epidermal cells, trichomes, and epicuticular waxes are
verified. The petiole and leaf anatomical characteristics (e.g., vascular bundle pattern,
cuticle, crystal), fruit and seed micromorphological characteristics (e.g., follicle surface,
testa ornamentation) provide useful information to be considered in systematic studies
within Sorbarieae. Results of phylogenetic analyses indicate that tribe Sorbarieae
is strongly supported as monophyletic group and two major clades divided within
Sorbaria . A taxonomic revision of genus Sorbaria based on the pollen morphology,
fruit and seed micromorphology, phylogenetic framework, and numerical results from
external morphological examination of herbarium specimen, including types is also
presented. Here, I suggested two new sections, combinations, and one new variety:
Sorbaria sect. Sorbifolia J.-H. Song & S.-P. Hong, sect. nov. (ined.), Sorbaria sect. Kirilowii
J.-H. Song & S.-P. Hong, sect. nov. (ined.); S. kirilowii (Regel & Tiling) Maximowicz var.
arborea (C.K.Schneid.) J.-H. Song & S.-P. Hong, comb. nov. (ined.), S. kirilowii (Regel &
Tiling) Maximowicz var. dubia (C.K.Schneid.) J.-H. Song & S.-P. Hong, comb. nov. (ined.); S.
sorbifolia (L.) A.Braun var. glandulosa Nakai ex J.-H. Song & S.-P. Hong, var. nov. (ined.).