Launaea sarmentosa (Willd.) Kuntze., an edible perennial herb, is critically considered an endangered species due to its habitat destruction. In vitro L. sarmentosa propagation was therefore conducted to preserve this plant. Two types of explants including leaf and stolon were applied to induce the multiple shoots by culturing on Murashige and Skoog (MS) medium supplemented with BA (0, 1, and 2 mg/L) and 2,4-D (0, 1, 2, and 4 mg/L). The optimal shoot induction medium for both explants was MS medium containing 2 mg/l BA (presented 100 % shoot induction). Roots were induced by various types and concentrations of auxins [1-naphthalene acetic acid (NAA), indole-3-acetic acid (IAA), and indole-3-butyric acid (IBA)]. The highest percentage of rooting (70.00 ± 11.05 %) was obtained from stolon-derived shoots on MS medium supplemented with 0.1 mg/l IAA. One-hundred percent survivability was presented after transforming plantlets into a mixture of soil, sand, and peat moss (1:1:1). Starch, protein, and lipid were accumulated in leaves detected by histochemical technique. The obtained information will be a useful tool for mass propagation of L. sarmentosa and to obtain basic knowledge for plant accumulating substances. HIGHLIGHTS GRAPHICAL ABSTRACT

Launaea sarmentosa (Willd.) Kuntze, a threatened coastal species endemic to the Andaman coastline of Thailand, is undergoing significant population decline due to habitat degradation. Despite its ecological and economic importance, limited knowledge exists regarding its anatomical adaptations to coastal environments, knowledge that is essential for effective conservation and restoration strategies. This study aimed to comprehensively investigate the vegetative anatomy of L. sarmentosa and to identify taxonomically significant features that reflect its adaptation to environmental stressors. Samples of leaves, stems, stolons and roots were collected from Mai Khao Beach, Phuket and examined using paraffin embedding and light microscopy techniques. The results revealed several adaptive features, including amphistomatic leaves, thick cuticlar layers, homobaric leaf structure and the formation of periderm in stems and roots. Stomatal density was significantly higher on the adaxial surface compared to the adaxial surface, indicating differential regulation of gas exchange. The presence of a thick cuticle and epidermis further highlights its adaptations to the harsh coastal environment, characterized by high light intensity and drought conditions. Stolons exhibited chlorenchyma and stomata, suggesting their role in photosynthesis and water regulation. These anatomical traits reflect the ability of L. sarmentosa to thrive in dune habitats and provide essential information for future conservation and habitat restoration initiatives. Understanding these adaptations is crucial for the effective preservation and rehabilitation of this species.

A new species is described from Thailand, Collotheca laddae sp. nov ., and a pictorial key to all Collotheca species and subspecies recorded in Southeast Asia is provided. The new species was discovered during a freshwater zooplankton identification workshop. This species is characterized by a five-lobed infundibulum with very small lateral lobes and short vibratile setae. The pictorial key was developed from a review of original descriptions and illustrations of all valid species of Collotheca and is designed to facilitate species-level identification based on live specimens. The discovery of C. laddae sp. nov ., together with the absence of new regional records for more than a decade, indicates that sessile rotifer diversity in Southeast Asia remains insufficiently explored.

Launaea sarmentosa (Willd.) Kuntze, a creeping herb native to the Andaman coasts of Southern Thailand, faces significant threats from habitat loss and environmental changes following the 2004 tsunami. This study investigated its ecological and anatomical characteristics across 4 coastal sites in Phuket and Phang-Nga Provinces. The parameters were categorized into 4 groups: plant traits (including photosynthetic pigment contents and anatomical features), upper soil layer features (e.g., sand, clay, chloride, magnesium, and pH), lower soil layer features (e.g., sand, silt, nitrogen, phosphorus, calcium, chloride, and magnesium), and climatic variables (air temperature and relative humidity). Sampling was conducted during the rainy season (November 2023) and the dry season (April 2024). Results revealed significant seasonal and site-specific differences in plant traits. Shoot density and below-ground fresh weight were highest during the rainy season and at sites with moderate sunlight. The chlorophyll a/b ratio varied significantly between seasons and sites, while the total chlorophyll/carotenoid ratio differed between sites only. Leaf anatomical features also showed seasonal variation, with upper and lower epidermis thickness, mesophyll thickness, and upper epidermal cell area being greater in the dry season, while the lower epidermal cell area remained unchanged. In the upper-layer soil, chloride content was influenced by season, while sand, clay, magnesium, and pH varied significantly between sites. In the lower-layer soil, sand, silt, chloride, and magnesium varied seasonally, while nitrogen, phosphorus, and calcium showed site-specific differences. Climatic factors also showed both seasonal and spatial variability, with cooler temperatures and higher humidity during the rainy season, particularly at moderately sunny sites. In summary, L. sarmentosa appears to favor conditions with partial sunlight, moist soils, and clay-rich substrates. These conditions were associated with greater shoot density and biomass. The findings highlight the role of seasonal and site-specific factors and offer useful guidance for conservation and coastal ecosystem management. HIGHLIGHTS Seasonal variation affects shoot density, the below/aboveground biomass ratio, the chlorophyll a/b ratio, as well as the thickness of the leaf epidermis and mesophyll in Launaea sarmentosa. Site-specific variation also influences the growth of sarmentosa, which favors moderately sunny environments. Soil properties at the study sites were investigated for the first time. In the upper layer, Cl serves as a seasonal predictor, while soil pH, organic matter, P, K, Ca, and Mg act as site predictors. In the lower layer, Cl and Mg vary temporally, while N, P, and Ca vary spatially. The present study emphasizes the need for habitat conservation to protect natural populations of sarmentosa. GRAPHICAL ABSTRACT