Floral Anatomy in the Saxifragaceae Sensu Lato. Iv. Baueroideae and Conclusions

Abstract

This paper presents a description of the floral anatomy and morphology of Bauera rubioides and a general discussion of how the patterns of variation in floral characters among the subfamilies of the Saxifragaceae sensu lato described in this and previous papers correlate with the patterns of variation in other types of characters (i.e., embryology, biochemistry, etc.). Major conclusions are: (1) The Saxifragoideae, including Ribes, forms a rather homogeneous taxon with regard to floral and other characters. (2) Since the high degree of similarity in floral structure between Itea (Iteoideae) and members of the Saxifragoideae is not correlated with similarities in a number of other characteristics, the affinity between the two probably is not as strong as floral characters suggested. (3) The differences in floral structure between Parnassia (Parnassioideae) and the Saxifragoideae are correlated with differences in other characteristics, and on this basis the taxon should be excluded from the family. (4) Brexia and Ixerba (Brexioideae) are strikingly dissimilar in floral structure and therefore probably do not belong in the same subfamily. Tentatively, Ixerba may find a place in the Escallonioideae, but the relationships of Brexia remain problematical. (5) Bauera (Baueroideae), which has a floral structure quite distinct from that of the Saxifragoideae, shares a number of similarities in embryology, pollen morphology, vegetative anatomy, and biochemistry with the Cunoniaceae and is probably better placed in that family than in the Saxifragaceae. (6) Kirengeshoma palmata (Kirengeshomoideae) should be transferred to the Hydrangeoideae and the whole removed from the Saxifragaceae, since certain floral characters which isolate the group from the Saxifragoideae are correlated with differences in embryology, pollen morphology, leaf and nodal anatomy, and cytology. (7) The Escallonioideae remains a major taxonomic problem because so little information is available on the members of this taxon.

Comparative floral structure and systematics in Celastrales (Celastraceae, Parnassiaceae, Lepidobotryaceae)

“…Hallier (1901) placed Parnassia with Sarraceniales, then with Saxifragaceae (1903), but again (1908) with Droseraceae and Sarraceniaceae. A separate family was also supported by Takhtajan (1959), Huber (1961) and Bensel & Palser (1975b). Furthermore, serological studies of seed proteins showed no affinity of Parnassia with Saxifragaceae (Grund & Jensen, 1981).…”

Comparative floral structure and systematics in Crossosomatales (Crossosomataceae, Stachyuraceae, Staphyleaceae, Aphloiaceae, Geissolomataceae, Ixerbaceae, Strasburgeriaceae)

“…(Bentham & Hooker, 1862–1867; Eichler, 1878; Engler, 1930), or Escalloniaceae (Hutchinson, 1969). Bensel & Palser (1975a, b) stated that Ixerba is not related to Brexia based on floral structure, resembling more that of Escalloniaceae. Thorne (2000) placed Ixerba in Escalloniaceae, and Brexiaceae in Celastrales, but Takhtajan (1997) in Ixerbaceae of Brexiales (Celastranae).…”

A new species of Chrysosplenium (Saxifragaceae) from Northeastern China

“…Chrysosplenium L. (Saxifragaceae) is a genus of small succulent and fragile herbs characterized by tetramerous flowers with petaloid sepals (Bensel and Palser 1975, Soltis 2007, Soltis et al 2001). It is composed of approximately 70 species, mainly distributed in temperate regions of the Northern Hemisphere, except for two disjunctive species in Chile (Hara 1957, Spongberg 1972, Pan 1986, Ye and Zhang 1994, Wakabayashi and Takahashi 1999, Han and Kang 2012, Bhaumik 2014, Kim and Kim 2015, Liu et al 2016, Kim et al 2018, Wakabayashi et al 2018).…”