Berberis hypoxantha C.Y. Wu ex S.Y. Bao (Berberidaceae), a new record for Vietnamese flora

In October-November 2015, a collaborative plant collection expedition was carried out in national parks of northern Vietnam. The staff of the Plant Resources Center (PRC) of the Vietnam Academy of Agricultural Sciences, Hanoi, and the US Department of Agriculture, Agricultural Research Service National Clonal Germplasm Repository in Corvallis, Oregon, participated. During the expedition, an unusual species of Berberis was observed. This species was found in Hà Giang Province in wet evergreen mixed forests on karst limestone between 1500 and 1600 m. Its range in Hoang Lien Son National Park, Lào Cai Province, was at elevations of 1500 to 2500 m, under a dense tree canopy mixture of broad leaved and semi-evergreens on upland reddish soils that were weathered from granite and eroded limestone. Subsequently, samples were examined and voucher specimens were prepared. The objective of this manuscript is to describe the species in preparation for potential addition to Vietnamese flora. This species had bright yellow flowers, evergreen leaves, and deep purple black fruits, but it differed from other Berberis in the region. Although it appears to belong to section Wallichianae, its lack of significant spines and the obscure veining of the leaves are a particular combination not recorded elsewhere in the section. The sample proved to be Berberis hypoxantha C.Y. Wu ex S.Y. Bao, previously known only from the type collection from Nanchang Gongshe, Xichou, Xian in SE Yunnan province, China, and is newly recorded from three locations in Hà Giang and two in Lào Cai province, Vietnam. Vouchers from Lào Cai province were deposited in the Hanoi National University Museum: HNU 022576 and HNU 022577.