Heterotheca subaxillaris (Lam.) Britton & Rusby (Asteraceae-Astereae), a new record to the flora of Egypt

It is widely known that the flora of Sinai Peninsula is distinctly affected by that of its neighboring regions. In this study, Numerous specimens of Heterotheca subaxillaris (Lam.) Britton & Rusby (Asteraceae-Astereae) are collected along El-Arish – Rafah Road, N. Sinai, Egypt. In an attempt to confirm the plant identification with its relatives in the Egyptian Asteraceae, it is confirmed as a new generic and specific record to the flora of Egypt, increasing the number of Asteraceae in Egypt to 235 species and 100 genera. H. subaxillaris is native to North America but was reported as an introduced species in the neighboring countries outside its native range, as in Palestine, Lebanon, Morocco and Spain and Argentina. Detailed description of macro and micro morphological characters of H. subaxillaris is provided. In the future, Priority should be given to assessing the phytosociological impact of this aggressively invasive species on the local flora.