Piper motuoense X.W.Qin, F.Su & C.Y.Hao, a new species of Piperaceae from Xizang, China, is described and illustrated in this paper. The new species resembles P. yinkiangense and P. anisotis, but it can be readily distinguished from the compared species by several characteristics. Gonophyll leaves are chartaceous and the leaf secondary vein count is 7–9, with the outermost pair being very weak when there are nine veins. Additionally, the apical pair arises 2–4 cm above the base and the leaf base is asymmetrical, with bilateral petioles that cling and heal together. Pistillate floral bracts are sessile, with 3, 4 or 5 stigmas. The description of the new species includes photographs, detailed descriptions, notes on etymology, distribution and habitat, as well as comparisons with morphologically similar species.

Piper puerense (Piperaceae), a new species from Yunnan, China, is here described and illustrated. Detailed morphological comparisons between the newly discovered species and other members of Piper indicate that Piper puerense is similar to Piper curtipedunculum, from which it differs in that stems of the new species are densely pubescent when young, glabrous when mature, leaf blades ovate, 8.5–12 cm × 4.3–6.5 cm, spike peduncle 15 mm long, nearly two times larger than the petiole; female inflorescence 12–18 cm long, male inflorescence 20–30 cm long, fruit obovate in shape, 1.0–1.5 mm in diameter.

Stauranthera floribunda F.Su, C.Y.Hao & K.Tan, a new species of Gesneriaceae from Yunnan, China, is described and illustrated here. It is morphologically similar to S. grandifolia Benth. in the shape of corolla, stigma, leaves and the number of stamens. However, it can be readily distinguished from the compared species by its dense cymes, leaf indumentum, lack of a corolla spur, calyx colour and stamen shape. The description of the new species, photographs, detailed descriptions, notes on etymology, distribution and habitat, as well as comparisons with morphologically similar species, are provided.

Vanillin, the principal aromatic compound in vanilla, is primarily derived from mature pods of vanilla (Vanilla planifolia Andrews). Although the biosynthetic pathway of vanillin has been progressively elucidated, the specific key enzymes and transcription factors (TFs) governing vanillin biosynthesis require further comprehensive investigation via combining transcriptomic and metabolomic analysis. For this study, V. planifolia (higher vanillin producer) and V. imperialis (lower vanillin producer) were selected. Time-series metabolomics analysis revealed 160–220 days after pollination (DAPs) as the critical phase for vanillin biosynthesis. Combined time-series transcriptome analysis revealed 984 upregulated differentially expressed genes (DEGs) in key periods, 2058 genes with temporal expression, and 4326 module genes through weighted gene co-expression network analysis (WGCNA), revealing six major classes of TFs: No Apical Meristem (NAC), Myb, WRKY, FLOWERING PROMOTING FACTOR 1-like (FPFL), DOF, and PLATZ. These TFs display strong regulatory relationships with the expression of key enzymatic genes, including P450s, COMT, and 4CL. The NAC TF family emerged as central regulators in this network, with NAC-2 (HPP92_014056) and NAC-3 (HPP92_012558) identified as key hub genes within the vanillin biosynthetic gene co-expression network. The findings of this study provide a theoretical foundation and potential target genes for enhancing vanillin production through genetic and metabolic engineering approaches, offering new opportunities for sustainable development in the vanilla industry and related applications.

Piper hongheense (Piperaceae), a new species from Yunnan Province of China, is here described and illustrated. Morphologically it is similar to Piper boehmeriifolium and Piper boehmeriifolium var. glabricaule, from which it can be easily distinguished by the combination of characters: height 0.7–1 m, leaves oblong-lanceolate to lanceolate, 10–16 cm × 2.5–4 cm, infructescences ±0.6 cm in diam., berries and bracts white when mature. The description of the new species includes photographs, a detailed description, notes on etymology, distribution and habitat, as well as a comparison with morphologically similar species.

Based on the evidence from morphology, literature survey and specimen examination, Piper curtipedunculum (Piperaceae) is recognized as independent species which is used to be a synonym of Piper pedicellatum. Piper boehmeriifolium var. glabricaule, Piper terminaliflorum and Piper yunnanense are considered as new synonyms of P. pedicellatum to which they are similar by a series of morphological characters. And the morphological differences, similarities and geographical ranges of these plant are clarified.