Re: D. rotundifolia X D. intermedia

Peter Cole (
Thu, 02 Nov 1995 10:27:18 GMT

"Michael.Chamberland" <23274MJC@MSU.EDU> writes:

> Thanks, I have that issue (Vol 14, # 1, March 1985). I think I have
> found D. rotundifolia X D. intermedia here in Michigan. However, I am not
> sure how to differentiate this hybrid from D. X anglica (D. rotundifolia X
> D. linearis).

Hmm, I don't know what else this hybrid might be called, but I
think there are some not inconsiderable problems in viewing it
as conspecific with Drosera anglica HUDS. Although it is
morphologically similar to D. rotundifolia x D. linearis (from
which Schnell surmises it may have evolved ['Carnivorous Plants
of the United States & Canada' 1976],) there are differences at
a cellular level (the fertile D. anglica has larger cells [ibid].)
It would also set an unusual (unprecedented?) exception for fertile
Drosera hybrids from comparatively unrelated species (see below
re: D. filiformis.)
Schnell's reference to this possibility of a hybrid nature (as well
as origin,) for D. anglica is, as far as I can tell, not shared by
the other authors in my CP library - Slack, Cheers, Temple,
Lecouffle, Pietropaolo all accord D. anglica specific rank.
But most tellingly (IMHO,) there is the problem of how the species
comes to be found widely distributed around the northern hemisphere,
for the most part in the complete absence of D. linearis - a species,
if anything more tolerant of varied growing conditions than D.
anglica (certainly in my own experience as far as PH, water quantity
and quality are concerned.) From a common-sense point of view, it
seems scarcely credible that linearis could have been sufficiently
widespread in the past to have parented so many populations of D.
anglica, only to disappear so completely, leaving its relatively
fussier offspring thriving.

I suppose it is possible that the North American plants are in fact
a separate but extremely similar taxon derived from "an accident of
cell division" [ibid], but in the absence of any published evidence
supporting this (unless anyone knows of such research?), or any
personal experience of N. American plants, I don't give it much
Perhaps the three species evolved together from a more primitive
common ancestor? My understanding of genetics and palaeobotany are
woefully inadaquate to assess the probable course of evolution in
this rather complex case, but whichever path was taken, the end
result is to my mind a distinct species. Any thoughts anyone? Jan?

IME, D. anglica self-pollenates reliably, so the species can be
readily distinguished from any similar hybrids after flowering.
D. rotundifolia x intermedia (D. X beleziana,) is a considerably
smaller plant than D. anglica, and is recognisable by the pigment
in the leaf tissue as well as the tentacles (D. anglica has
unpigmented lamina.) I find it a lot harder to distinguish this
hybrid from intermedia (only slightly smaller and similar
pigmentation,) which I also grow - it was a bit of a mistake to
plant them all together in a large bowl outdoors, so now I can only
be 100% sure when I come to collect the seed.

Jan's database entry for anglica makes the 'official' stance clear

N: +[Drosera anglica {HUDS.}]
P: FL.ANGL.ED.2:135 (1778)
T: [Drosera longifolia {L.}] p.p. (LINN)
L: Can., Alaska, Washington, Ore., Ca., Idaho, Montana, N Dakota, Minnesota, W
isconsin, Mich, Maine, USA, N & C EU, N Spain, N Italy, Macedonia, Romania, R
ussia, Japan, Hawaii
XN: (30) 40 {ROSENBERG}
XNP: BER.DT.BOT.GES.21:110 (1903)
TEXT: 0077.html Key to Drosera of North America {GLEASON 1958}

> To make matters worse, Schnell indicates that D. rotundifolia X
> D. anglica plants exist (D. X obovata). The latter is confusing, since I
> thought fertile D. anglica was an amphidiploid? Perhaps D. rotundifolia
> manifests several ploidy levels?

There are other hybrids of D. anglica - notably D. anglica x D.
spathulata 'Kansai' (D. X nagamoto,) D. anglica x D. spathulata
'Kanto' (D. X wateri,) and anglica x intermedia (D. X anglimedia? -
probably not :^)
They are of course all sterile. In fact the only non-sterile
Drosera hybrid that springs to mind would be D. X 'California
Sunset', the fertility of which is a factor Schnell bases his
argument on for subspecific rather than separate specific status
for the two parents (D. filiformis filiformis + D. filiformis
tracyi.) ['Drosera filiformis Raf.: One Species or Two?' CPN 24:1]

By implication, though he mentions the possibility, Schnell does
not seem convinced that D. anglica is actually a hybrid by nature,
and skirts around the issue in his book. I would love to see the
"pretty good evidence" he mentions for a hybrid 'origin' for D.
anglica if anyone knows where it was published?

Happy growing,