Panax stipuleanatus Tsai is a type of medicinal plant within north-west Vietnam. In this study, inter simple sequence repeat markers were employed to investigate the genetic diversity of naturally distributed populations classified by habitat for this species. Genetic diversity at the species level was moderate (H eT D 0.254; PPB T D 96.02%). Genetic diversity was not equal in two populations. The result showed higher population genetic diversity in the Lao Cai region (H eBX D 0.266; PPB BX D 91.48%) as compared to those located in Lai Chau region (H eHT D 0.235; PPB HT D 84.66%). The interpopulation gene differentiation was small (G STP D 0.03) with the genetic distance among populations was D P D 0.0103. Gene flow within populations was as high as Nm D 7.36.

A new variety of Panax, P. vietnamensis var. langbianensis is described from Lang Bian Mountain, Lam Vien Plateau in southern Vietnam. It is visually distinct from other two varieties of P. vietnamensis (var. vietnamensis, var. fuscidiscus) by having the shorter petiolules 8–11 mm long, leaflet apex acuminate, pedicels 0.4–0.6 cm, petals smaller, disk prominent, and styles typically 2 (or rarely 1). The recognition of the new variety is supported by the evidence of molecular sequence data from three markers (ITS1-5.8S-ITS2, 18S rRNA and partial matK) in addition to morphological consideration. The new variety is known only from one population from the locality where the type specimens were collected. The species occurs in an area of only approximately 1 km2 with a population size of approximately 100–200 individuals. Therefore it should be regarded as critically endangered (CBB2acb (ii,iii,v); C2a(i); E) according to the IUCN Red List Categories and criteria.

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Genetic diversity and variation of three naturally distributed Rhododendron moulmainense populations in the Lam Vien Plateau of Vietnam were analyzed using ISSR and SCoT markers separately and data from the two types of markers were then combined to show the overall results. Based on combined data, the genetic diversity parameters of the Tuyen Lam population were percentage of polymorphic bands (PPB) = 28.79%; genetic heterozygosity (He) = 0.1041; Shannon index (I) = 0.1552. The corresponding parameters were PPB = 37.88%; He = 0.1434; I = 0.2131 in the Hon Nga population, and PPB = 46.21%; He = 0.1857; I = 0.2709 in the Bidoup population. At the species level in Lam Dong province, the corresponding parameters were PPB = 62.12%; He = 0.1747; I = 0.2756. The average of pairwise genetic similarity coefficients among investigated individuals of Tuyen Lam population was 0.973, of Hon Nga population was 0.911, and of Bidoup population was 0.895. The genetic differentiation and the number of migrants per generation among investigated populations were GSTS = 0.1735 and Nm = 2.3824 individuals, respectively. Genetic distance between Tuyen Lam and Hon Nga populations was 0.0399, between Tuyen Lam and Bidoup populations were 0.0621, and Bidoup and Hon Nga populations were 0.0670. Data generated by both marker types and the combined revealed similar trends of genetic diversity levels among the studied populations. The SCoT data showed higher values of genetic diversity and population gene differentiation than did the ISSR data, but the latter showed higher gene differentiation among sampled individuals in the study populations. Comparing the values of Polymorphism Information Content (PIC) for discriminatory ability; Effective Multiplex Ratio (EMR) for several revealed loci and/or efficiency of the primer-marker system; Marker Index (MI) for the efficiency of used method; and Resolving Power (Rp) between used techniques indicated that discriminatory ability, efficiency, and ability of the ISSR primer combinations were higher but using SCoT marker system was more efficient than ISSR marker system for evaluating genetic diversity.