Flora and Phytochorology of Lahij Governorate of Yemen: Systematic Revision of the Family Boraginaceae s.l.

Abstract

Knowledge of plant diversity within the family Boraginaceae s.l. in southern Yemen flora remains limited. This study aims to address that gap by providing a taxonomic revision of Boraginaceae s.l. in the flora of Lahij Governorate, South Yemen. The surveyed species include a morphological review and analyses of life span, growth forms, life forms, and phytogeographical affinities. Twenty-one species are identified and grouped into eight genera. For each species, its current classification, accepted names, synonyms, photographs, and distribution information are presented to aid in identification. Of the borage species found, there were 71.43% perennials and 28.57% annuals. Chamaephytes (38.10%) and therophytes (28.57%) were the most common types, with a strong Sudano–Zambezian chorological affinity, both biregional and pluri-regional. Phytogeographical analysis revealed that pluri-regional elements constitute the most significant proportion of the recorded species (42.86%), indicating that widespread species dominate the borage taxa. Heliotropium, Cordia, and Euploca were the most species-rich genera. One species (Cynoglossum yemenense) is endemic to Yemen. The study also provides six dichotomous keys for borage species in the Lahij Governorate: one for the family and five for the genera.