What is "polygala vulgaris"

Gang-flower \Gang"-flow`er\, n. (Bot.) The common English milkwort ( Polygala vulgaris), so called from blossoming in gang week.
--Dr. Prior.

Milkwort \Milk"wort`\, n. (Bot.) A genus of plants ( Polygala) of many species. The common European Polygala vulgaris was supposed to have the power of producing a flow of milk in nurses.

Note: The species of Campanula, or bellflower, are sometimes called milkwort, from their juice.

Rogation \Ro*ga"tion\, n. [L. rogatio, fr. rogare, rogatum, to ask, beg, supplicate: cf. F. rogation. Cf. Abrogate, Arrogant, Probogue.]

1. (Rom. Antiq.) The demand, by the consuls or tribunes, of a law to be passed by the people; a proposed law or decree.

2. (Eccl.) Litany; supplication.

   He perfecteth the rogations or litanies before in use.
   --Hooker.

   Rogation days (Eccl.), the three days which immediately precede Ascension Day; -- so called as being days on which the people, walking in procession, sang litanies of special supplication.

   Rogation flower (Bot.), a European species of milkwort ( Polygala vulgaris); -- so called from its former use for garlands in Rogation week.
   --Dr. Prior.

   Rogation week, the second week before Whitsunday, in which the Rogation days occur.

Polygala vulgaris, known as the common milkwort, is a herbaceous perennial plant of the genus Polygala belonging to the Polygalaceae family.