Pelargonium glutinosum, P.denticulatum and Pelargonium cultivar 'Filicifolium'

Richard Clifton finds in Decadic Pelargonium Cultivars, № 5, that this name may first have been used in 1893 by "J.S." possibly "Saul" possibly Europe but the records rather anonymous on this point. Herr Elsner gives later authors but I note that the International Register abandoned all this data in favour of only referencing Mrs. D. Miller's 1996 book Pelargoniums (p. 101), which has a leaf outline and where she states that 'Filicifolium' is a cultivar selection of P. denticulatum, NOT of P. glutinosum. POSA-3 states that the 2 species can easily be distinguished despite BOTH species having clammy or sticky leaves, because the leaves of P. denticulatum (POSA, 2:52) are very much more finely divided (P. glutinosum, POSA-3:58). The obvious method to find out would be to raise seedlings to see if they "break down" to one species or the other.

Herr Elsner (first published in our "Summer News", 1986, p. 11):

"Some years ago by courtesy of Mr. Henry Weller of Ewell, I got some cuttings of P.'Filicifolium' I am glad to possess these plants with their nice fern-like leaves. Since I intended to label them according to the International Code of Botanical Nomenclature, Istudied my literature about Pelargonium.

1.   R. Knuth does not mention the name 'Filicifolium' in his monograph Geraniaceae (Tome IV vol.129 of Engler's Das Pflanzenreich, 1912)

2.   Derek Clifford, in the 2-nd edition of his book Pelargonium including the Popular Geranium (1970) records 'Filicifolium' in Part 2E "Scented-Leaved Pelargoniums" with the synonyms 'Fernaefolium' and suggests Geranium multifidum of Andrews (circa 1805). Clifford speaks of clammy leaves.

3.   Helen van Pelt Wilson in The Joy of Geraniums (1972) remarks on it as P. denticulatum 'Filicifolium', 'Fern-leaf Geranium' with sticky leaves.

4.   Rita Scheen-Prias, in her book Geranium als Lief-hebbery (1975) mentions "P.x filicifolium" as a natural hybrid of P. denticulatum with sticky leaves.

All this information is not satisfying. Only the characterization of sticky or clammy leaves corresponds. My plants have sticky leaves too. Only P. glutinosum (Jacq.) L'Her. ex Ait. (syn. Geranium viscosum Cav. non P. Mill.) I has sticky leaves too, so far as I am informed. This species is very similar to 'Filicifolium', more similar than P. denticulatum, which has hairy but not sticky leaves. Then I thought it is allowed to suppose that P. 'Filicifolium' is a bud mutation of P. glutinosum, which may be propagated true only vegetatively. To prove this I self-pollinated my plants in 1980 and 1981. I gained 3 (three) seeds. They were sown in 1981. All  three plants have the same growth and the same leaves as P. glutinosum.

The conclusionis that actually, P.'Filicifolium' is a bud mutation of P. glutinosum.

R. Clifton: we published Herr Elsner's full item in our "Summer News" 1986 p.11 and I had a brief check of the next 2 Newsletters but didn't find any reply. His point about seedling identity has subsequently been ignored, though it seems incontrovertible that he has demonstrated that 'Filicifolium' is not a P. denticulatum derivative but a P. glutinosum derivative. Herr Elsner says his P. denticulatum is hairy not sticky. This is certainly how in looks in POSA but perhaps the stickiness varies with cultivation or time of year; certainly most people find it IS sticky: both it and P. glutinosum have glandular hairs from which this must flow.

POSA-3 tells us that both P. denticulatum and P. glutinosum have glutinous leaves, though they show P. denticulatum as hairy-glandular rather than sticky in Sweet's "bird-lime" manner. The leaf-teeth on P.denticulatum are not ultimately sharp as they are in P. glutinosum. Members will know that I don't keep up with cultivars, so has anyone any report investigating 'Filicifolium'? Otherwise, I think Herr Elsner did the job in 1981 and reported it in 1986.

Mrs. Miller in her book just states it "is" a form of P. denticulatum without giving any data other than she saw similar plants in S. Africa. We have had problems like this before, for horrid example P. 'Graveolens', where there is a very nice species P. graveolens with rose scented leaves but what we get in cafes here is some terrible back-crossed thing that LOOKS the same. Has Mrs. Miller seen plants of P. glutinosum and misidentified them? To add my half-pennyworth, I have seen a colony of P. glutinosum in South Africa, containing various forms, one of which seemed to me identical to 'Filicifolium', but I note, that Prof. van der Walt in Bothalia 15 (3,4) p.362 shows a habitat form identified by him as P. denticulatum identical to 'Filicifolium'. It is quite possible that there are several "lines" of 'Filicifolium' in cultivation, some derived from P. glutinosum some from P. denticulatum, others by hybridization between the 2. The main reason we do not normally "notice" cultivars of Pelargonium is that there is a perfectly good Society dedicated to those cultivars, The Pelargonium and Geranium Society. Let them worry.

It's bad enough trying to "understand" the species - see our items on sect. Otidia.

Botany: the 2 species are admitted by Prof. van der Walt to be very close but he does not discuss hybrids, although the 2 species' distributions overlap about 80%. He DOES say in both Bothalia and POSA that P. glutinosum occurs in 3 forms one of which has "deeply incised leaves". The 2004 DNA study reported in Taxon 53(1) does not mention P. glutinosum while P. denticulatum is found to be as close as it is possible under their methods to "P. quercifolium" which we suppose was ex-habitat from Prof. van der Walt and therefore as in POSA-3:118. If the distance between P. denticulatum and P. glutinosum is too small to retain both as separate species then the overall taxon would be P. glutinosum first named in 1787 by Prof. Jacquin because the earlier name Geranium viscosum Scop., in his Del. FI. Faun. vol.2 p.27 & 1.14 (1786) is illegitimate due to the prior use by Mr. P. Miller as Geranium viscosum Mill., in Gard. Dict.ed.8, p.20 (1768) which was Erodium ciconium L'Her., says Prof. Guittonneau, while P. denticulatum was not named til 1797. Thus if Taxon was implying there was only 1 species, it picked the wrong name. I noted in analysis of the Taxon article that it had used several illegitimate names and some that seemed to be "nursery names", non-existent in botanical terms.

Conclusion 2013: Herr Elsner demonstrated that the clone 'Filicifolium' received by him was a form of P. glutinosum. Whether P. denticulatum is properly separate from the "deeply incised" leaf forms of P. glutinosum is doubtful.

article source: Clifton R., Elsner W., Pelargonium glutinosum, P. denticulatum and Pelargonium cultivar 'Filicifolium', The Geraniaceae Group News, Summer, 2013, p. 7