Pollen germination on the surface of 0.70% agar in water for 12 hours at 20-22C.
The germination of pollen could vary between the flowers age and condition.
All results must be copied 2-3 times. Since pollen may lose its capacity to germinate
by rain, dryness, heat, age, and poorly developed flowers ...
When I collected pollen, I tried to take it from the newly opened anthers
In polyploid plant the cells could have different numbers of chromosomes (sport) mosaics
so sometimes the pollen can germinate (make pollen tubes) from some flowers.
SAMPLE = Rhododendron hybrid
P.Germ. = Pollen grain germination %
Ref. = Reference person.
...HE = Hans Eiberg
...JP = Dr. João Loureiro, Dr. Silvia Castro, José Cerca, and Mariana Castro (John Perkins) JP
...TE = Tom Eeckhaut (p.75) TE
..JRJ = J. R. Jones (p.30-)JRJ
...LW = Larry Wallance (personal information)
...KT = Kristian Theqvist (personal information)
Ploidy = Number of chromosome set
Weighing In: Discovering the Ploidy of Hybrid Large Leaf Elepidote Rhododendrons. J. Perkins et al. (More data here)
I am working on this web-site.

7 4N
Sample P. Germ. Ref. Ploidy Ref.
Arbendsonne 5 HE
Admiral De Ruyter 4N JP
Adonis 20 HE
Aglo 2N JRJ
Aida 3N JP
Altaclerensis 4N JP
Angel Powder 3N JP
Anilin 0 HE
Anabelle 8 HE
Anna 2N JP
Antoon van Welie 4N JP
Anuschka 0-1 HE
April Rhapsody 3N JP
April Rose no pollen 2N JRJ
Ariel 4N JP
Arnold Piper Polyploid? JP
R. atlanticum X (R. atlanticum x R. molle) 4N JP
August Lamken 2 HE 3N JP
Azurro 0 HE
Azurwolke 50 HE
Bad Eilsen 0 HE
Beaté Céleste 4N JP
Bernstein 15 HE
Berry Rose 20-40 HE
Bijou des Amateurs 4N JP
Billini 2 HE
Blaufeder 4N TE
Blewbury 50< HE
Blue Diamond 80 HE
Bluenose 3N JP
Blue Peter 5-15 HE
Blueshine Girl 5 HE
Blue Target 4N JRJ
Bouquet de Flore 4N JP
Brasilia 10 HE
Broughtonii 3N JP
Birgitte 10-40 HE
Brittanica 0 dry HE
Bronze Unique 3N, F JP
Buketta 50-85 HE
Bureavii Hanzel 1-10 HE
Butterfly 0 HE
campylocarpum Margor 0-1 HE
California Gold 2N JRJ
Caractacus 2 HE
Cardinal 4N JP
Carmen 70 HE
Caroline Albrook 30 HE
Casille 2N JP
Catawbiense Album 15 HE
Catawbiense Grandiflorum 5 HE
Catherina von Toll 10 HE
Chetco 4N? ?
Cheyenne 2N JRJ
Chickor 2N TE
China AM 10-40 HE
Choptank 4N JP
Clivia 0 HE
Coastal Spice 2N JRJ
Coleman's May Pink 4N JP
Comte de Fladre 4N JP
Corneille 4N JP
Cotton Candy 3N JP
Countess of Derby 4N JP
Cowslip 1 HE
Cream Crest 10 HE
Creekside 2N JP
Crest 80 HE
Croceum Tricolor 3N JP
Cunninghams White 25 HE
Curlew 2N TE
Cymodocee 4N JP
Cynthia 3N JP
Daviesii 3N JP
Deep Rose 3N JP
Doreen Gale 4N JP
Diadem 0/20 HE
Diamant 5 HE
Diandi 0 HE
Diane 2N JP
Directeur Charles Baumann 4N JP
Discolor x Vauban 2 HE
Django pollen steril egg steril 3N JP, KT
Dora Armateus 2N JRJ
Doreen Gale 4N JP
Doberluger Weisse 10 HE
Durante Alle 4N JP
Effner 20 HE
Ehrengold 15 HE
El Camino 3N JP
Electum 4N JP
Elfenfee no pollen HE
Elisabeth Lockhart 10 HE
English Roseum 5 HE
Epoch 4N JP
Erato 20 HE
Euan Cox 2N TE
Eugénie 4N JP
Evening Sky 3N JP
Everlasting 2N JRJ
Fantastica 2N JRJ
Fastuosum Flore Plenum 0 HE
Fénelon 4N JP
Feuerwerk x 1 HE
Fireflash x Buttercup 4N JP
Flameola Incarnata 4N JP
Flava 10 HE
Freya 3N JP
Improved Fragrantissimum 2N JRJ
Frosthexe No pollen 3N JP
Furnivals Daughter 2-4 HE 2N ?
Gardendirektor Glocker no pollen HE 3N JP
Gardendirector Riger 0-1 HE
Gargantua 4N JP
Geisha Purple 0 HE
Gentle Giant 4N JRJ
George Maier 25 HE
Gertrud Schäle 10 HE
Gladywense 3N JP
Gletschernacht 4N JRJ
Gloria Mundi 3N JP, TE
Goldbukett no pollen HE
Golden Bee 2N TE
Golden Sunset 5-20 HE
Goldflimmer 5-80 HE 2N JRJ
Goldika 3-10 HE
Goldkrone 5-20 HE
Goldsworth Orange 2N TE
Gormer Watere 0 HE 3N JP
Graf Lennart 80 HE
Graf Zeppelin 2N JP
Grand Slam 4N JRJ
Grumpy 20 HE
Görlitz 0-5HE
HabaShan 2N TE
Hachmann's Feurschein 4 HE
Hallelujah 3N JRJ
Héroine Plena 4N JP
Heureuse Surprise 4N JP
H.H.Hume 2N JP
Hillier's form 4N TE
Holger 70 HE
Hollandia 4N TE, JP
Hodspur red 20 HE
Hora 4N JP
Horizont Lakeside 2N JP
Horizont Monarch 4N JRJ, JP
Horizont Monarch x Point Defiance 4N JRJ
Horizont Monarch x Rwain 4N JP
Hotei 2N JP
Humboldt 20-50 HE
Hummingbird 15 HE
Hyperion 5 HE
Igneum Novum 4N JP
Il Tasso 4N JP
Insigne x 5-15 HE
Intermedium 15 HE
Jacksonii 10-20 HE
Jackwill 0 HE
Janet Blair 8 HE 2N JRJ
Jean Marie de Montaque 2-20 HE
Jean Marie 2N JP
Jenny Lind 4N JP
Jingle Bells 2N TE
Josephine Klinger 3N JP
Juliana Nova 4N JP
Julius Caesar 4N JP
Kalinka 3 HE
Karin 90 HE
Karl Saurborn 15 HE
Kehr's White Ruffles 3N JP
Kermesina 50 HE
Kokardia no pollen HE
Kupferberg 2N TE
Lavendula no pollen HE
Leibuir 4N JP
Lelia 4N JP
L'Engin 4N JP
Lem's Monarch 4N JRJ, JP
Linda 15 HE
Lissabon 20 HE
Looye's Blue 4N JP
Madame Cavalho 2 HE 2N JP
Madame Gustave Guillemot 4N JP
Mancando 8 HE
Manitou 2N JP
Marietta 50 HE
Marie Verschaffelt 4N JP
Marius Koster 4N JP
Marketta Flame 3N JP
Marlene Vuyk 10 HE
Marlis 0 HE
Mars 0 HE
McNabii 2N JRJ
Maxicat 2N JRJ
Melba's Dream 2N JP
Minerva 4N JP
Miniatum Floribundum 2N JP
Moerheims Pink 0 HE
Monica 0 HE
Morgenrot 10 HE
Mrs.T.H. Lowinsky 10 HE
Mysterious Maddenii 2N JRJ
Nancy Evans 2N TE
Nancy Waterer 4N TE, JP
Narcissiflora 4N
Nacelle 2N JP
Nova Zembla 20 HE 2N JRJ
Obergärtner H. Robeneck 80 HE
Old Port 70 HE
Onkel Dines 10 HE
Orangina 5-10 HE
Oscar I 4N JP
Pastel #6,7,20 2N JP
Patricia Barmold 40 HE
Percy Wiseman 2 HE
Perfecta 4N JP
Phebe 3N JP
Phidias 3N JP
Phyllis Korn 3N JP
Phyllis Korn x Trude Webster 5N JP
Piepmatz 5 HE
Pink Puff 2N JP
Pink Pearl (fertile) 8 HE 3N JP
Point Defiance JRJ, JP
Polar Bear 2N JP
Pontica Album 3N JP
Praecox 70 HE
Princess Anne 80 HE
Princess d'Orange 4N JP
Ptarmigan 60 HE
Purple Gem 3N JP
Purple Splendour 20 HE
P.J. Mezitt 3 HE 2N JRJ
P.J.M. Regal 2 HE
Polar Beer 2N JRJ
Praxitèle 3N/4N JP
Puget Sound 2N JRJ
Queen Anne x Gold Dust 2N JRJ
Quentin Metsys 4N JP
Racine 4N JP
Radistrotum 5 HE
Ramapo 3N JP
Ramolet 3N JP
Raphael de Smet 4N JP
Rendezvous 2N JP
Ribera 4N JP
Riplet 10 HE
Roland 0 ? HE
Rosata 0 HE
Rose Marie 4N JP
Rosita 5 HE
Rothenburg <1 HE 3N JP
Rwain 3N JP
Rwain x L'Engin 4N JP
Sammetglut 20 HE
Santiam 3->4N? ?
Shamrock 2N TE
Shappo 40 HE
Scarlet Wonder 0 HE
Schlaraffia 10 HE
Schneebukett 20 HE
Schneeglanz 70 HE
Schneespiegel 1 HE
Scintillation no pollen HE
Silberwolkwe 1 HE
Simona 0 HE
Snehvide 1-10 HE
Snow (Kurume azalea) 2N JP
Solidarity 3N JP
Solidarity, OP 3N JP
Southern Cloud 3N JRJ
Souvenir du Président Carnot 4N JP
Speciosum Yellow #3 4N JP
Summer Peach 2N JP
Sunny 4N TE
Surprime Rose 10 HE
Tatjana 30 HE
Taurus 0 HE 3N JRJ
Teniers 4N JP
Titian Beauty 0 HE
Toy 2N JP
Trude Webster 4N JP
Unique 4N TE
Vanessa 10 HE
Van Houttei Flore Pleno 3N JP
Veesprite 3N JP
Velasquez 3N JP
Virginia Richard 0 HE
Viscy Hobbie 0 HE 3N TE
Vitalio 30 HE
Vulcan 2N JRJ
Vulcan's Flame 2N JRJ
Vulcan's Tetraploid 2N + 4N JRJ
Wardii x viscidifolium 2 HE
Washingtotn State Centennial 4N ?
Wee Bee 2 HE
Weston's Crescendo 2N JP
Whidbey Island 4N ? LW
White Ruffles 3N JRJ
Windbeam 2N JP
Windsome 0-8 HE
Wingard's Gold 4N JP
Wisechap 2N JP
yakushimanum x haematodes 3 HE
yak. x pachysanthum 10 HE
yak. x rex 5 HE
yak. x strigillosum 10 HE
yak. x thomsonii 25 HE
yak. tsariense 10 HE
Yellow Hammer 0-1 HE 7-8N TE
References:
http://www.ces.ncsu.edu/fletcher/mcilab/publications/jones-2008.pdf
Hotei and Nancy Evans are pollen sterile R. niveum 6N in some clones

> Below are the results of the xx tested,  2017.
> 
> 2x
> Adriaan Koster
> Bethany Jade
> Bruns Sirius
> Dagmar
> Doctor H.C. Dresselhuys
> Doctor V.H. Rutgers
> Don Juan
> Donald Watener
> Double Besse
> George Hardy
> Gotham Rheingold
> Gunborg
> Heinje's Venezia
> Irmelies
> Isadora
> Kathe Heinje
> Lady Longman
> Loder's White
> Mrs E C Stirling P
> Professor J.H. Zaaijer P
> Scandinavia
> Shoreham
> Sir Robert Peel
> Wanna Bee
> 
> 3x
Anita Gehnrich (Gehnrich) UM 
Anna Rose Whitney (Van Veen, 1954) F NM 
Annie E. Endtz (Endtz 1939) DM
August Lamken (Hobbie, 1942)
Auguste Van Geert  
Beauty of Littleworth (Mangles, 1884) 
Betty Wormald (Koster, 1907) F 
Broughtonii (Broughton, 1840) F 
Caruso (Hachmann 1990) NM
Charis (Hachmann 1990) NM
Cotton Candy (Henny and Wennekamp, 1958) F UM 
Cynthia (Standish and Noble, 1856) F 
Dame Nellie Melba (Loder, 1926)
Denali (Elliott 1987) NM 
Django (Hachmann 1985)
Ebony Pearl (sport, 1966) 
El Camino (Whitney, 1976) NM 
Frentano (Hachmann 1989) NM
Gartendirektor Rieger (Hobbie, 1947) 
Gomer Waterer (Waterer, 1900) F DM 
Grace Seabrook (Seabrook, 1965) UM 
Halfdan Lem (Lem 1967) UM
Hallelujah (Greer, 1958) 
Hank's Folly (Schannen) NM 
Hollandia (Endtz 1938) DM
Johnny Bender (Seabrook 1960) F UM
Julia Caroline (Brockenbrough, 1990) NM
Kaye Player  
Lady of Spain (Lofthouse, 1966) NM 
Lucky Strike (Van Veen, 1958) NM 
Lydia (Greer, 1963) F NM 
Markeeta's Flame (Markeeta, 1960) UM 
Markeeta's Prize (Markeeta, 1970) UM
Melville  
Newcomb's Sweetheart (Newcomb 1968) NM
Opal Thornton (Thornton) NM 
Pearce's American Beauty (Pearce, 1930) F 
Phyllis Korn (Korn, 1969) F DM 
Pink Pearl (Waterer, 1892) F DM 
Platinum Pearl (Greer, 1983) F NM 
Queen Mary (Felix and Dijkhuis 1950) DM
Romilda (Hachmann 1990) NM
Rothenburg (von Martin, 1944) 
Rwain (Colombel, 1993) F NM 
Solidarity (Schannen, 1969) F UM
Souvenir de Doctor S. Endtz (Endtz 1924) DM 
Steredenn (Colombel) NM 
Sugar Pink (Greer, 1960) NM 
Super Dog (Bones) NM 
Taurus (Mossman, 1962) F UM 
Topsvoort Pearl (sport, 1935) 
Val d'Aulnay (Croux and Fils, 1984) F 
Van (Van Veen, 1930) NM 
Viscy (Hobbie 1950) UM

> 
> 4x
Antoon van Welie (Endtz, 1930) 3X2 
Aristide Briand (Endtz 1950) 3XQ
Brigg's Red Star (Briggs) T 
Cherry Cheesecake (Briggs) T * 
Countess of Derby (White, 1913) 3X3 
diaprepes `Gargantua' (Stevenson, 1923) 
Doctor A. Blok (Endtz 1937) 3XQ
Doctor Arnold W. Endtz (Endtz 1927) 3XQ
Doreen Gale (Sanders) 4X4 
Friesland (Endtz 1958) 3XQ
Gentle Giant (Sanders, 1992) 4X3
Germania (Hobbie 1956) 4X2 
Gorgeous George (Sanders) 4X4 
Grand Slam (Greer, 1982) 4X3 
Horizon Jubilee (Brockenbrough) * 
Horizon Monarch (Brockenbrough, 1981) 2X4 
Jan Dekens (Endtz 1940) 3XQ
Janet Ward
Le Fouesnantais (Colombel, 1997) 4XQ 
Legend (Barlup) 4X4 
Lem's Monarch syn Pink Walloper (Lem, 1965) 2X4 
L'Engin (de la Sablière) 4X2 
Marinus Koster (Koster, 1937) 
Pink Goliath (van Nes 1958) 4XQ
Point Defiance (Lem, 1970) 2X4
Pride of Roseburg 
Professor Hugo de Vries (Endtz 1958) 3X2
Reverend Paul aka White Owl(Sumner 1975) 4X4
Summer Joy (Kehr) T 
Super Nova (Briggs) T * 
Trude Webster (Greer, 1960) 4x4
TT166 
Very Berry (Greer, 1988) 4X2 
XXL (ID'Flor)

> 
> 5x
Haithabu (Hachmann 1991) 4XQ
White Ginger (Barlup 2001) 4X3

> 

F indicates a fertile triploid.
T indicates a chemically induced tetraploid. 
P indicates a diploid with a polyploid ancestor. 
S indicates a diploid with a tetraploid parent. 
U indicates a diploid with a tendency to produce unreduced gametes. 
DM indicates a triploid resulting from a triploid parent. 
NM indicates a triploid resulting from a tetraploid parent. 
UM indicates a triploid resulting from 2 diploid parents. 
2X4 or 4X2 indicates a tetraploid resulting from a diploid and a tetraploid parent. 
3X2 indicates a tetraploid resulting from a triploid and a diploid parent. 
3X3 indicates a tetraploid resulting from 2 triploids parents.
3XQ indicates a tetraploid resulting from at least one triploid parent.
4X4 indicates a tetraploid resulting from 2 tetraploid parents. 
4X3 indicates a tetraploid or pentaploid resulting from a tetraploid and a triploid parent. 
4XQ indicates a tetraploid or pentaploid resulting from a tetraploid parent


> John Perkins
> Salem, NH
>