Two Extraordinary New Pseudopetiolate Carex Species from Vietnam (sect. Hemiscaposae, Cyperaceae)

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Carex kucyniakii is a poorly known, morphologically unusual Vietnamese sedge (sect. Hemiscaposae, Cyperaceae) that is part of an early diverging lineagewithin the genus. Fieldwork in Lao Cai Province resulted in the rediscovery of this species near its type locality and the detection of significant variation in the morphology of plants in nearby populations. Subsequent morphological andmolecular studies revealed that C. kucyniakii is a complex of three species. These taxa are endemic to the southern slopes of the Hoang Lien Mountains, in Lao Cai Province, and exhibit extraordinary morphological features including the widest leaves known for any Cyperaceae (pseudopetiolate and up to 12 cm), and for some taxa pink-red inflorescences. Of the three species recognized in the complex, C. kucyniakii is characterized by a combination of glabrous perigynia, scales, and peduncles, while in C. geographica sp. nov. and C. thinii sp. nov. these structures are pubescent/scabrous. In addition, the scales and perigynia in C. kucyniakii are green or brown while those in C. geographica and C. thinii are suffused with pink or red. Differences in pistillate and staminate scale morphology and anther length distinguish the latter two species. The Vietnamese Carex flora contains a high proportion of morphologically exceptional and poorly understood taxa, many from early diverging lineages in the genus. Our findings support the supposition that Indochina and East Asia could be the center of origin for the world's largest flowering plant genus and that the sedge flora of northern Vietnam contains a number of taxonomic novelties still remaining to be discovered.