Cytology, palynology, and taxonomy of Asteropyrum and four other genera of Ranunculaceae

Abstract

A karyomorphological study of two species in Asteropyrum (Ranunculaceae) and five in presumably related genera (one each in Caltha , Coptis , and Dichocarpum and two in Thalictrum ) reveals close similarities between Asteropyrum and Caltha , but obvious differences between Asteropyrum and Coptis , Dichocarpum , and Thalictrum , in some karyological features, such as the structure of the interphase nuclei, chromosome size, basic chromosome number, and condensation behaviour of chromosomes during the mitotic prophase. The chromosomes of Asteropyrum are categorized as being of the R-type and the basic chromosome number is confirmed as x = 8, indicating a possible close affinity of Asteropyrum to members in the subfamily Helleboroideae, in particular to Caltha and its allies. Asteropyrum peltatum and Asteropyrum cavaleriei are shown to be more or less differentiated from each other in gross morphology and palynology, and somewhat independent in geographical distribution, albeit with intermediate forms occurring where their distribution zones overlap. It seems justifiable to treat them as two subspecies of A. peltatum .

Molecular phylogeny and historical biogeography of Caltha (Ranunculaceae) based on analyses of multiple nuclear and plastid sequences

“…Based on the combined analysis of molecular and morphological data by Wang et al (2009), Caltha seemed to be sister to Asteropyrum. The close relationship between Caltha and Asteropyrum was also suggested by the karyological study (Yuan & Yang, 2006b). For that reason, we chose Asteropyrum as the outgroup for our biogeographic analysis.…”

“…Its flower is actinomorphic with petaloid sepals and lacks petals, and fruits are follicles (Tamura, ). According to its morphological and chromosomal (Ranunculus‐type) characters (Langlet, ; Gregory, ; Yuan & Yang, , ), Caltha was considered very closely related to Calathodes Hook. f. & Thomson, Trollius L., and Megaleranthis Ohwi, and these four genera constituted the subtribe Calthinae Bentham in tribe Helleboreae DC.…”

Structural variation of the complete chloroplast genome and plastid phylogenomics of the genus Asteropyrum (Ranunculaceae)

“…cavaleriei can be easily distinguishable by their size and shape of leaves. Intermediate forms between the two subspecies in morphology and palynology are sometimes present at their overlapping zones 24 and can be either more similar to ssp. peltatum or to ssp.…”

“…1E,F). According to Yuan & Yang 24 , it can be recognized as an intermediate form but more similar to ssp. cavaleriei .…”

“…1E,F). Thus, A. cavaleriei has often been treated as a subspecies of A. peltatum 24 .

Figure 1Field photographs of Asteropyrum taxa. ( A , B ) Asteropyrum peltatum ssp.

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