Found the info I was looking for
Hibiscus section Muenchhusia contains five North American species, H. coccineus, H. dasycalyx, H. grandiflorus, H. laevis, and H. moscheutos all 5 have been recorded to have a chromosome number of 19, and they are known to form hybrids relatively easy
Here are a few other Hibiscus chromosome counts:
Hibiscus asper (36)
Hibiscus bifurcatus (36)
Hibiscus caesius Garcke (36)
Hibiscus calyphyllus Cav. (80)
Hibiscus cannabinus (36)
Hibiscus citrinus (22)
Hibiscus costatus (18)
Hibiscus denisonii (84 & 168)
Hibiscus elatus (90, 60, 96)
Hibiscus grandidieri (32)
Hibiscus hirtus (64)
Hibiscus flagellifomis (72)
H. syriacus (2n=4x=80)
H. sinosyriacus (2n=4x=80)
Hibiscus calycinus(2n=4x=80)
Hibiscus archeri 2n=4x=84)
H. paramutabilis (2n=82)
'Pink Giant' (2n=6x=120)
H. schizopetalus (Masters) Hook.f. (2n=42)
H. mutabilis L. (2n=92)
H. rosa-sinensis L. (84)
H. rosa-sinensis cv. DoubleRainbow (105)
H. rosa-sinensis cv. Flavo-plenus (138
H. rosa-sinensis cv. Carminatus (147)
Queen, Bride, Evening Star (46)
Snow Queen, Snow drift, Cooperi , Snow Flake , Snow Star, (54)
Coral Star, Major Gaje , Prof. Kaul , Sheila Kaul , Sunrise , Viceroy , Victory (63)
Ajanta , Leo, Cardinal, (68)
Brilliantissimus , Nizam , Star , Venus , Aphrodite , Rose Queen , Mary Walker ( 72)
Ali pore Beauty , J ohnwalker , Pride of Lanca ( 77)
Archeri , Pearl , Dawn of Day , Sunset , Exquisite (84)
Model Pride , Amethyst, King George, Perfection, Queen Mary, Percy Lancaster , Harbour , Light, Chrome, Deepa, Kaul , Opal, Lord Kitchner, (90)
Venustus, Sulphur Queen, Lipstick, 'Darling, Sweet Heart, Prince of Wales, Crown Prince (96)
Laxmi , Treasure, Karoon, Drab, Honey (112)
Australian Rose', 'Raja', 'Rani', 'Tara', 'Crest', 'Vesta, Neptune, Diana, Brilliant, Bashful, Amazon (132)
Giant Rose, Kadam Rasool, Mars, Chaste, Everest, Bridegroom, Admiral, Rose Queen (144)
