Comparative Study of Leaf Morphology in <i>Aster hispidus</i> Thunb. var. <i>leptocladus</i> (Makino) Okuyama (Asteraceae)

Abstract

The comparative morphology and anatomy of leaves in the serpentine endemic <i>Aster hispidus</i> Thunb. var. <i>leptocladus</i> (Makino) Okuyama and its close relative <i>A. hispidus</i> var. <i>hispidus</i> were examined. Our morphological analysis revealed that the leaves of <i>A. hispidus</i> var. <i>leptocladus</i> were significantly smaller and narrower than those of <i>A. hispidus</i> var. <i>hispidus</i>. In particular, our anatomical analysis indicated that a decreased cell number of the horizontal axis of a leaf was involved in <i>A. hispidus</i> var. <i>leptocladus</i>. This was the same process as the changing pattern of the leaves of rheophytic species, and so, similar morphological leaf modifications occurred under different selection pressures of the serpentine soil and flooding frequency of river-stream

Adaptative Leaf Morphology of Eurya japonica Thunb. (Ternstroemiaceae) in Serpentine Areas

“…The characteristic vegetation in serpentine outcrops is associated with the presence of edaphic endemic species, and the morphological characteristics may differ from those of ancestral species in non-serpentine areas (Kruckeberg, 1954). In fact, previous studies have indicated that serpentine-adapted plants have narrow leaves (Hayakawa et al, 2012;Ohga et al, 2012;Kumekawa et al, 2013Kumekawa et al, , 2016, indicating that these reductions could be a response to an edaphic environment that exhibits nutrient deficiencies in serpentine soils (Kruckeberg, 1954). Our results indicated that E. japonica in the serpentine populations had thicker leaves and smaller stomata than those of the inland populations (Table 2), suggesting that E. japonica had been morphologically and anatomically modified to adapt to serpentine soils.…”

“…var. leptocladus (Makino) Okuyama (Asteraceae) (Hayakawa et al, 2012;Kumekawa et al, 2013) and have been considered a plant adaptive mode in serpentine areas. Moreover, the fact that the reduced stomatal density was also found among different lineages suggested that this modification was likely an adaptation to serpentine areas.…”

Morphological and Anatomical Analyses of the Serpentine Ecotype of Adenophora triphylla var. japonica (Campanulaceae)

“…However, the leaf index differed significantly between the two investigated serpentine areas. Hayakawa et al (2012) observed that the leaf index of the serpentine species, Aster hispidus var. leptocladus, differed according to serpentine areas, and proposed that leaf morphology was involved not only in stenophyllization, but also in minitualization.…”

“…Most of these species have morphological characteristics such as narrower leaves and thinner stems. For example, Hayakawa et al (2012) demonstrated that the narrow leaf of the serpentine endemic Aster hispidus Thunb. var.…”

Foliar Adaptations in Aster hispidus var. insularis (Asteraceae)

“…Conversely, these varieties could be result of ecotypic differentiation in A. hispidus in Japan driven by different ecological factors prevailing in the habitats it occupied. To substantiate the premise, the study by Hayakawa et al (2012) involving A. hispidus and of the stenophyllous A. hispidus var. leptocladus showed decreased cell number of the horizontal axis of a leaf based as an adaptation.…”