In apogamous ferns, all offspring from a parent are expected to be clonal. However, apogamous species frequently show a large amount of morphological and genetic variation. Cyrtomium fortunei and its relatives, which are distributed throughout Japan, are reported to be apogamous triploids, but show large and continuous morphological variation. Four varieties of C. fortunei have been recognized. We sought to determine whether an apogamous species has genetic variation, and if so, whether this variation relates to morphological variation within local populations. Among 224 individuals growing in four distantly located populations in Japan, where several varieties grow together, two rbcL types (α and β) and eight allozyme types (A-H) were identified. Several different genetic clones were detected in the local populations examined. Only individuals that could be morphologically identified as C. fortunei var. intermedium, based on bicolored indusia, had rbcL β and allozyme type H, and thus, were genetically differentiated by their nuclear and plastid genomes from the other three varieties of C. fortunei. The other three varieties shared the same rbcL (α), making correlation between allozyme types and varieties, especially genetic differences between var. fortunei and var. clivicola, unclear.
Ligustrum micranthum Zucc. (Oleaceae), a small tree endemic to the Bonin Islands, was examined in the field to clarify its sexual system. In the local populations examined on Chichi-jima, all individuals appeared to be hermaphroditic, having a pistil with an ovary and two stamens. They were divided into two morphological groups, however, one having anthers with pollen (staminate fertile) and the other having anthers without pollen (staminate sterile). Staminate sterile individuals set fruit under open pollination. However, staminate fertile individuals showed various fruit production under open pollination. Five plants of the 19 staminate fertile individuals examined did not set fruit for the two years of our observations. This is the first report of sexual polymorphism in Ligustrum. Such a sexual system in L. micranthum might have evolved within the Bonin Islands.
The first study of floral dimorphism and the sexual system in natural populations of a Japanese species of Thymus is presented. Thymus quinquecostatus was previously reported to show a dimorphism in flower size. We investigated floral variation and mode of reproduction to clarify the degree of floral dimorphism and to determine the sexual system. The length of the lower and upper lips, the corolla tube, and the calyx usually showed a monomodal frequency distribution within a population. The length of the outer and inner stamens, however, showed a bimodal distribution. Based on these floral characters the populations were tentatively divided into two discrete morphs: one with long (L) and one with short (S) stamens. The anthers of the L-stamen morph usually produced fertile pollen, while the anthers of the S-stamen morph completely lacked fertile pollen, or poorly developed, abortive pollen grains. Both L- and S-stamen morphs produced fruits and seeds in natural populations. The findings suggest that floral dimorphism in T. quinquecostatus may be an example of gynodioecy, as reported in several other species of Thymus. Reproductively, pistillate plants show significantly higher fruit and seed production than hermaphrodites, as in some gynodioecious species.
Homalomena kualakohensis is described as a new species from Kelantan, Peninsular Malaysia. An updated key to Peninsular Malaysian species of Homalomena Cyrtocladon group is provided, and the new species is illustrated.
Schismatoglottis inculta Kurniawan & P.C.Boyce and Homalomena vittifolia Kurniawan & P.C. Boyce are described and illustrated as a new species from Sulawesi. Recognition of these novelties takes the aroid flora of Sulawesi to 41 species of which 15 (>35%) are endemic. None of the 17 recorded genera are endemic, and one (Colocasia) is non-indigenous. Two species occur as adventives (Alocasia macrorrhizos and Amorphophallus paeoniifolius), and one (Colocasia esculenta) occurs semi-naturalized as an escape from cultivation as, a carbohydrate crop. A preliminary checklist of the Araceae of Sulawesi is offered, and keys to the genera, and to the Sulawesi species of Schismatoglottis and Homalomena, are presented.
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