Artur PLISZKO, Kinga KOSTRAKIEWICZ-GIERAŁT

The morphological intermediacy of Erigeron ×huelsenii (Asteraceae), a hybrid between E. acris and E. canadensis

Morphological intermediacy is considered the first evidence of hybridization in many plant studies. However, morphological intermediacy does not always provide hybrid origin and can be a result of divergence. In this study, the authors revised the morphological intermediacy of Erigeron ×huelsenii, a putative hybrid between the Eurasian E. acris s. str. and North American E. canadensis, using the character count procedure, a method that allows distinguishing hybridity from divergence. The measurements were made on herbarium specimens, including 100 specimens of E. acris s. str., 100 specimens of E. canadensis, and 50 specimens of E. ×huelsenii, which were collected in northeastern and southern Poland in 2013-2016. Among the 15 characters selected for the character count procedure, the hybrid showed intermediacy in 12 characters. The deviation was very significant (P < 0.05) and therefore the hypothesis of hybridity was fully accepted. Moreover, details of indumentum and receptacle characters of the hybrid and its parental species were visualized using scanning electron microscopy. The morphological characters of E. ×huelsenii presented in this study seem to be useful in the proper identification of all the hybrids between E. canadensis and E. acris s. l.

Keywords:

Character count procedure, Erigeron, hybrid indumentum, scanning electron microscopy micrographs,

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