The Ovule Number Variation Provides New Insights into Taxa Delimitation in Willows (<i>Salix</i> subgen. <i>Salix</i>; Salicaceae)
2023
Alexander M. Marchenko | Yulia A. Kuzovkina
<i>Salix babylonica</i>, <i>S. alba</i> and <i>S. fragilis</i> are closely related species characterized by the lanceolate, acuminate and serrulate leaves. The boundaries between them are defined by relatively few diagnostic characters, and their identification is not fully solved. Recent studies have demonstrated that the number of ovules present in the ovaries of the willow flower can assist in the identification of the species. The detailed ovule data, characteristic for flowers of each species, <i>S. babylonica</i>, <i>S. alba</i> and <i>S. fragilis</i>, and variation in the number of ovules per ovary were documented using many representatives of these species from various geographic regions. The data included the minimum and maximum number of ovules per valve and per ovary and the percentages of valves with a specific number of ovules in a catkin. Some intermediate genotypes and clusters with similar ovule indexes were observed. The important character for the identification of <i>S. babylonica</i> was the presence of valves with 1 or 2 ovules in the ovaries; <i>S. fragilis</i> had valves with 3 ovules while <i>S. alba</i> had the greater number (4–12).
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