Notes on the narrow endemic of Armenia, Pyrus browiczii Mulk. (Rosaceae)

Pyrus browiczii Mulk. is a narrow endemic of the Vayots Dzor province of Armenia. It is the only pear species from the East Asian Pyrus section Pashia native to Armenian flora. Since the description by Ya. I. Mulkidzhanyan in 1969 so far P. browiczii was known by the type and single specimens in fruits. During the present study, P. browiczii was collected and observed in nature in flowering and fruiting phases. Article contains data on species taxonomy, ecology and particulars of habitat, complete description of the species, it is illustrated by original photos.


Introduction
Armenia is a center of high diversity, polymorphism and narrow endemism in the genus Pyrus L. (Mulkidzhanyan, 1969b;Browicz, 1993). About 32-34 species of four sections, Pashia Koehne, Pyrus, Xeropyrenia Fed., Argyromalon Fed., are recognized in the Armenian flora, of which 18 species are endemics for Armenia and Southern Transcaucasia (Akopian, 2007(Akopian, , 2010a. Pyrus browiczii Mulk. was first described by Ya. I. Mulkidzanyan (1969a)  location, reflecting the main trends of formation and speciation processes in the genus: from the ancient acute-serrate or aristate-dentate, glabrous, broad-leaved mesophilic forms to xerophytic forms of pears with narrow, small, densely pubescent leaves. The ancestors of the mesophilic species were components of the ancient tertiary forest flora, the refugia of which were preserved in East Asia. In Transcaucasia, according to V. N. Gladkova (1990), they are represented by such species as P. pyrifolia (Burm. f.) Nakai, P. browiczii Mulk., P. caucasica Fed., P. hyrcana Fed., P. zangezura Maleev.
Pyrus browiczii is the only pear species from the East Asian Pyrus section Pashia that grows in Armenia. It should be noted that the section Pashia is represented in the Caucasian flora rarely by single taxa: by the local variety P. pyrifolia (Burm. F.) Nakai var. talyschensis Gladkova in the Talysh flora (Gladkova, 1988) and by P. pyrifolia (Burm. f.) Nakai var. culta (Makino) Nakai in the garden culture of Transcaucasia (Fedorov, 1954).
So far, P. browiczii has been known only from type specimens, collected by J. I. Mulkidzhanyan et al. in 1968 and the later single samples in fruit stage, stored in the Herbarium (ERE) of the Department of Plant Taxonomy and Geography of the Institute of Botany NAS RA.
During expeditions in May and October of 2019 in Vayots Dzor province, P. browiczii was discovered in the area of "locus classicus", where new herbarium specimens were collected from. P. browiczii was described (Mulkidzhanyan, 1969a) by specimens, collected in the plant fruiting period, and the diagnosis of the species did not involve the features of inflorescences and flowers ("flowers unknown"). After the study of the existing herbarium material in ERE and comparing it with new collections of P. browiczii, as well as due to observations made in nature during the flowering and fruiting phase of the species, we found it necessary to supplement its description ( Fig. 1).

Material and methods
The study was based on P. browiczii ERE Herbarium material and on the new materials collected from species area in the Vayots Dzor province of Armenia during expeditions in 23 V 2019 and 11 X 2019. Materials represent both flowering and fruiting phases. Morphological characteristics of P. browiczii specimens were studied using Stereo Microscope MBC-9. Photos of the plant and their details were done with digital camera NIKON D3400.  (Fig. 2).

Taxonomy and Description
Distribution. Darelegis floristic region of Armenia. Gorge of the river Yeghegis, in the vicinity of villages Hermon (Kavuschuk) and Vardaovit (Gulliduz). Seldom. Narrow endemic of the Vayots Dzor province of Armenia (Fig. 3).
Flowering observed in April -May, fruiting in September -October.
Protection Category. Critically endangered species, included in the Red Book of Plants of RA (Akopian, 2010b). The area of occupancy is less than 10 km 2 . The limiting factors are restricted extent of occurrence and area of occupancy as well as anthropogenic factors influence. The population is represented by single individuals far apart from each other. Seed productivity is low, vegetative weak propagation is noted. There are currently no measures to protect the species in the habitat. Within the present study, some seedlings of P. browiczii were transplanted from nature into the living collection "Flora and Vegetation of Armenia" of the Yerevan Botanical Garden NAS RA for conservation ex situ.