What does “Ex” signify?

I have found the answer in wiki –
http://en.wikipedia.org/wiki/Author_citation.
Please, tell me if “ex” has other meaning.
Wikipedia seems to be partly correct as example is partly correct. These examples should help
46.4. A name of a new taxon must be attributed to the author or authors of the publication in which it appears when only the name but not the validating description or diagnosis was ascribed to a different author or different authors. A new combination or a nomen novum must be attributed to the author or authors of the publication in which it appears, although it was ascribed to a different author or to different authors, when no separate statement was made that they contributed in some way to that publication. However, in both cases authorship as ascribed, followed by “ex”, may be inserted before the name(s) of the publishing author(s).

Ex. 15. Seemann (1865) published Gossypium tomentosum “Nutt. mss.”, followed by a validating description not ascribed to Nuttall; the name may be cited as G. tomentosum Nutt. ex Seem. or G. tomentosumSeem.

Ex. 16. The name Lithocarpus polystachyus published by Rehder (1919) was based on Quercus polystachya A. DC. (1864), ascribed by Candolle to “Wall.! list n. 2789” but formerly a nomen nudum; Rehder’s combination may be cited as L. polystachyus (Wall. ex A. DC.) Rehder or L. polystachyus (A. DC.) Rehder.

Ex. 17. Lilium tianschanicum was described by Grubov (1977) as a new species and its name was ascribed to Ivanova; since there is no indication that Ivanova provided the validating description, the name may be cited as L. tianschanicum N. A. Ivanova ex Grubov or L. tianschanicum Grubov.

Ex. 18. In a paper by Boufford, Tsi and Wang (1990) the name Rubus fanjingshanensis was ascribed to Lu with no indication that Lu provided the description; the name should be attributed to Boufford & al. or to L. T. Lu ex Boufford & al.

Ex. 19. Green (1985) ascribed the new combination Tersonia cyathiflora to “(Fenzl) A. S. George”; since Green nowhere mentioned that George had contributed in any way, the combining author must be cited as A. S. George ex J. W. Green or just J. W. Green.

Ex. 20. However, R. Brown is accepted as the author of the treatments of genera and species appearing under his name in Aiton’s Hortus kewensis, ed. 2 (1810-1813), even when new names or the descriptions validating them are not explicitly ascribed to him. In a postscript to that work (op. cit. 5: 532. 1813), Aiton wrote: “Much new matter has been added by [Robert Brown] … the greater part of his able improvements are distinguished by the signature Brown mss.” The latter phrase is therefore a statement of authorship not merely an ascription. For example, the combination Oncidium triquetrum, based by indirect reference on Epidendrum triquetrum Sw. (1788), is to be cited as O. triquetrum (Sw.) R. Br. (1813) and not attributed to “R. Br. ex Aiton”, or to Aiton alone, because in the generic heading Brown is credited with authorship of the treatment of Oncidium.

46.5. The citation of an author who published the name before the starting point of the group concerned may be indicated by the use of the word “ex”. For groups with a starting point later than 1753, when a pre-starting point name was changed in rank or taxonomic position by the first author who validly published it, the name of the pre-starting point author may be added in parentheses, followed by “ex”.

Ex. 21. Linnaeus (1754) ascribed the name Lupinus to the pre-starting-point author Tournefort; the name may be cited as Lupinus Tourn. ex L. (1753) or Lupinus L. (see Art. 13.4).

Ex. 22. Lyngbya glutinosa C. Agardh (Syst. Alg.: 73. 1824) was taken up by Gomont in the publication which marks the starting point of the “Nostocaceae heterocysteae” (in Ann. Sci. Nat., Bot., ser. 7, 15: 339. 1892) as Hydrocoleum glutinosum. This may be cited as H. glutinosum (C. Agardh) ex Gomont.

Thank you very much Sir for this detailed meaning.
This means Dolichos falcatus Klein (of FBI. ii. 211; connected to FI. iii. 311) and Dolichos falcatus Willd. iii. 1047 (Flora Indica) can be interpreted as Dolichos falcatus Klein ex Willdenow.

I think yes, as per GRIN
The correct name according to both GRIN and The Plant List is P. trilobus L.
http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?14510
The Plant List, however, considers P. falcata Klein as spelling variant of P. falcatus Willd.  

Yes Sir, thank you once again.

 

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