Hybridity of lepidotes based on hybridizaton results

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Hybridity of lepidotes in Rhododendron subsection Ledum
based on some hybridization results
Kristian Theqvist, 7-Mar-2013, rev. 013

Note: The ploidy levels have not been updated to the latest results from flow cytometry tests! The table needs to be updated!

Note: The hybridity is based only on a small sample basis and several factors could affect on whether the pollination is successful. In some cases there was very scarce of pollen and that could be a reason for not getting seeds.
Criteria for "Hybridity evident": Seeds have germinated and at least some of the seed plants show features that differ from the wild R. tomentosum.

*Cross with another Rhododendron* species**
*Seed parent: R. tomentosum* (Ledum tomentosum, Ledum palustre), chromosome number 2n = 52, tetraploid**
Subsection (or section) in alphabetic order	Pollen parent / Species	2n	Year	Hybridity evident	Comment on seed plants
Boothia	leucaspis	?	2004	Yes	Germination 80 % resulting in 24 seed plants.
Caroliniana	minus (Milde)	26	2003	Yes	Germination 72 %. 20 seed plants. Very large variation, mostly vigorous, some weak ones.
	minus, pink (Göteborg)	26	2003	No	No seeds.
	minus (Bergianska)	26	2005	?	36 seeds but germination 0% and no plants.
Caroliniana (or x Rhododendron ?)	minus (Hachmann) Looks like a cross minus x ferrugineum?	?	2003	Yes	Germination 100 %. 21 seed plants. Very large variation, vigorous except one weak.
Cinnabarina	cinnabarinum var. cinnabarinum	104	2003	Yes	Germination 100 %. 41 seed plants. Very large variation, mostly vigorous, some quite small.
Cinnabarina	cinnabarinum var. xanthocodon	104	2005	Yes	Germination 40 %. 12 seed plants.
Edgeworthia	edgeworthii	26?	2006	tbd	35 seeds, germination successful.
Heliolepida	desquamatum (rubinosum)	52	2005	Yes	Germination 23 %. 7 seed plants.
Lapponica	fastigiatum SBEC 0804	52	2005	Yes	Germination 63 %. 19 seed plants.
	fastigiatum C&H 7022	52	2006	tbd	41 seeds, germination successful.
	hippophaeoides	26	2003	Yes	Germination 77 %. 25 seed plants. Very large variation, mostly vigorous, only few weak ones, some with chlorophyll defects that later on dissappered.
	hippophaeoides Album	26 (?)	2005	?	18 seeds but germination 0% and no plants.
	impeditum	26	2003	?	Too few weak seeds to make decisive conclusion on hybridity. No plants.
	impeditum	26	2004	Yes	Germination 43 %. 13 seed plants.
	lapponicum var. parvifolium	26	2004	Barely	Not many seeds. Germination 44 %. 4 seed plants.
	lapponicum, New Foundland	26	2004	?	Not enough pollen? No seed.
	lapponicum, New Foundland	26	2005	Yes	Germination 60 %. 18 seed plants.
	polycladum	52	2006	tbd	77 seeds, germination successful.
	russatum	52	2004	Barely	Not many seeds. Germination 30 %. 3 seed plants.
	russatum var. cantabile	52	2004	Yes?	A lot of seeds, but germination only 3 %. Only 1 weak seed plant.
	tapetiforme	78 (?)	2004	Yes	Germination 20 %. 6 seed plants.
	tsaii	?	2006	tbd	500 seeds, germination successful.
	yungningense	52	2004	Barely	Not many seeds. Germination 11 %. Only 1 seed plant.
	yungningense	52	2006	tbd	400 seeds, germination successful.
Ledum	diversipilosum (Ledum palustre var. diversipilosum )	52	2005	Yes	Germination 80 %. 24 seed plants.
	groenlandicum (Ledum groenlandicum )	52	2003	Yes	Germination 90 %. 35 seed plants. The seed plants looked more groenlandicum than tomentosum, some variation in leaf color and shape, some malformed ones. Extremely vigorous growth.
	hypoleucum (Ledum hypoleucum)	52	2003	Yes	Germination 55 %. 16 seed plants. Very large variation, some vigorous, some quite small.
	subarcticum (Ledum palustre ssp. decumbens)	26	2004	?	Not enough pollen? Only 3 small seeds, no germination, no seed plants.
	subarcticum (Ledum palustre ssp. decumbens)	26	2005	Yes	Germination 37 %. 11 seed plants.
	'Milky Way' (selected form)	52	2004	Yes	Germination 90 %. 27 seed plants.
Maddenia	veitchianum	26?	2004	Yes	Germination 60 %. 18 seed plants.
	lindleyi (picture © Glendoick Gardens)	26	2005	Yes	Germination 60 %. 18 seed plants.
	burmanicum	?	2006	tbd	57 seeds, germination successful.
Moupinensia	dendrocharis	26 (?)	2005	?	Only 2 small seeds, no germination, no seed plants.
Moupinensia	dendrocharis	26 (?)	2006	tbd	65 seeds, germination successful.
Pogonanthum	sargentianum	26	2004	?	Only 6 small seeds, no germination, no seed plants.
Rhododendron	ferrugineum	26	2005	?	13 small seeds, no germination, no seed plants.
	ferrugineum	26	2006	tbd	115 seeds, germination successful.
	ferrugineum Album	26 (?)	2005	Barely	70 seeds, mostly small, germination 10 %, 3 seed plants.
	hirsutum	26	2005	Barely	22 seeds, germination 9 %, 2 seed plants.
	x intermedium	26 (?)	2005	?	3 small seeds and lost.
Rhodorastra	dauricum	26	2003	Yes	Germination 22 %. 8 seed plants. Large variation, some with leaves without hairs.
	ledebourii (variety of dauricum)	26	2003	Yes	Germination 30 %. 14 seed plants. Large variation, some with leaves without hairs.
	mucronulatum var. chejuense	26	2006	tbd	43 seeds, germination successful.
Saluenensia	calostrotum ssp. keleticum	26	2004	?	Only 6 small seeds, no germination, no seed plants.
	calostrotum ssp. keleticum	26	2005	No	No seeds.
	prostratum	52 (?)	2005	No	No seeds.
	saluenense	26	2004	Yes	Germination 63 %. 19 seed plants.
Scabrifolia	spinuliferum (picture at www.rhododendron.dk, taken by Hank Helm)	26	2004	No	No seeds.
	spinuliferum (picture at www.rhododendron.dk, taken by Hank Helm)	26	2005	No	4 small seeds, no germination, no seed plants.
	spinuliferum (June Sinclair)	26	2004	Barely	Not many seeds. Germination 75 %. 6 seed plants.
Tephropepla	hanceanum 'Canton Consul'	?	2005	Yes	Germination 66 %. 19 seed plants.
Triflora, Augustinii / Triflorum Alliance	ambiguum	52	2004	Yes	Germination 40 %. 12 seed plants.
	augustinii	52	2004	Barely	Not many seeds. Germination 13 %. Only 1 seed plant.
	augustinii	52	2005	No	No seeds.
	chengshenianum (ambiguum)	52 (?)	2005	?	6 small seeds, no germination, no seed plants.
	concinnum	52	2004	Barely	Not many seeds. Germination 20 %. 2 seed plants.
	concinnum var. pseudoyanthinum	52	2004	Barely	Not many seeds. Germination 75 %. 3 seed plants.
	keiskei 'Yaku Fairy'	26 (?)	2004	Barely	Not many seeds. Germination 36 %. 4 seed plants.
Triflora, Yunnanense Alliance	hormophorum (yunnanense)	78 (?)	2005	?	3 small seeds, no germination, no seed plants.
Triflora, Yunnanense Alliance	yunnanense	78	2004	Yes	Germination 43 %. 13 seed plants.
Triflora, Oreotrephes Alliance	oreotrephes	78	2004	No	No seeds.
Triflora, Oreotrephes Alliance	oreotrephes	78	2005	?	Swelling seed pods disapperared
Section Tsutsusi	kiusianum	26	2003	No	No seeds.

*Cross with a Rhododendron* hybrid**
*Seed parent: R. tomentosum* (Ledum tomentosum, Ledum palustre), chromosome number 2n = 52, tetraploid**
Pollen parent / Hybrid in alphabetic order	Subsection (or section)	2n	Year	Hybridity evident	Comment on seed plants
'Aquamarin', (augustinii hybrid)	Triflora x	?	2004	No	No seeds.
'Biskra' (cinnabarinum Roylei Group x ambiguum)	Cinnabarina x Triflora	?	2004	Yes	Germination 55 %. 12 seed plants.
'Biskra' x cinnabarinum var. xanthocodon	(Cinnabarina x Triflora) x Triflora	?	2004	Barely	Not many seeds. Germination 7 %. Only 1 seed plant.
'Blumiria' (impeditum x ?)	Lapponica x ?	?	2003	Barely	Not many seeds. Germination 60 %. 5 seed plants. Large variation on few plants, a couple of vigorous ones.
'Charme La' minus Carolinianum Group x pemakoense Patulum Group	Caroliniana x Uniflora	?	2006	tbd	200 seeds, germination successful.
'Countess of Haddington' (ciliatum x dalhousiae)	Maddenia x	?	2005	?	3 small seeds, no germination, no seed plants.
'Curlew' ( ludlowii x fletcherianum) (picture © Glendoick Gardens)	Uniflora x Maddenia	?	2005	?	7 small seeds, no germination, no seed plants.
'Dörte Reich' (minus x cinnabarinum Concatenans) (picture © Glendoick Gardens)	Caroliniana x Cinnabarina	?	2003	Yes	Germination 67 %. 9 seed plants. Some variation, all very vigorous.
'Flämingperle' (hippophaeoides hybrid)	Lapponica x ?	52	2005	Yes	Germination 53 %. 16 seed plants.
'Isola Bella' (dauricum 'Artic Pearl' selfed) x fletcherianum 'Yellow Bunting'	(Rhodorastra x) x (Maddenia x)	?	2004	Barely	Not many seeds. Germination 30 %. 3 seed plants.
'Johnsonianum'	Unknown	?	2005	No	No seeds.
'Mother Greer' (hippophaeoides x ?)	Lapponica x ?	?	2003	No	No seeds.
'P.J.M. Elite' (minus x dauricum)	Caroliniana x Rhodorastra	?	2003	Barely	Germination only 25 %. 6 seed plants. Large variation, mostly vigorous.
'Princess Anne' (picture © Glendoick Gardens) (hanceanum x keiskei)	Tephropepla x Triflora	?	2004	Barely	Not many seeds. Germination 60 %. 6 seed plants.
'Puncta' (ferrugineum x minus var. minus, parentage uncertain)	Rhododendron x Caroliniana ?	?	2005	Barely	Only 11 seeds, germination 18 %, 2 seed plants.
'Ramapo' (fastigiatum x minus)	Lapponica x Caroliniana	?	2003	Barely	Not many seeds. Germination 38 %. 3 seed plants. Large variation on few plants, a couple of vigorous ones.
'Robert Seleger' (calostrotum ssp. keleticum x ?)	Saluenensia x ?	?	2003	No	No seeds.
'Schneeflöckchen' (trichostomum hybrid)	Pogonanthum x	?	2004	?	Only 6 seeds, no germination, no seed plants.

Note: 2n is the chromosome number. The chromosome numbers are mainly from the Rhododendron Year Book 1950.

Lepidote Crosses in 2003 using Rhododendron tomentosum as Seed Plant
Pollinations in 2004 using Rhododendron tomentosum as Seed Plant
Pollinations in 2005 using Rhododendron tomentosum as Seed Plant
Pollinations in 2006 using Rhododendron tomentosum as Seed Plant
Taxonomy of species in Rhododendron subsection Ledum