Question: Which has more species, Nothofagus or Rhododendron?

Context paragraphs:
Rhododendron catawbiense: Rhododendron catawbiense, with common names Catawba rosebay, Catawba rhododendron, mountain rosebay, purple ivy, purple laurel, purple rhododendron, red laurel, rosebay, rosebay laurel, is a species of "Rhododendron" native to the eastern United States, growing mainly in the southern Appalachian Mountains from Virginia south to northern Alabama.

Rhododendron: Rhododendron (from Ancient Greek ῥόδον "rhódon" "rose" and δένδρον "déndron" "tree") is a genus of 1,024 species of woody plants in the heath family (Ericaceae), either evergreen or deciduous, and found mainly in Asia, although it is also widespread throughout the highlands of the Appalachian Mountains of North America.  It is the national flower of Nepal.  Most species have brightly coloured flowers which bloom from late winter through to early summer.

Nothofagus: Nothofagus, also known as the southern beeches, is a genus of 43 species of trees and shrubs native to the Southern Hemisphere in southern South America (Chile, Argentina) and Australasia (east and southeast Australia, New Zealand, New Guinea and New Caledonia).  The species are ecological dominants in many temperate forests in these regions.  Some species are reportedly naturalised in Germany and Great Britain.  The genus has a rich fossil record of leaves, cupules and pollen, with fossils extending into the late Cretaceous and occurring in Australia, New Zealand, Antarctica and South America.  In the past, they were included in the family Fagaceae, but genetic tests revealed them to be genetically distinct, and they are now included in their own family, the Nothofagaceae (literally meaning "false beeches" or "bastard beeches").

Rhododendron minus var. minus: Rhododendron minus" var.  "minus, the Carolina azalea or Carolina rhododendron, is a rhododendron species native to the mountains of North Carolina, South Carolina and Tennessee. And Northeast Georgia.  It is commonly known as Rhododendron carolinianum in the horticultural trade.

Rhododendron ferrugineum: Rhododendron ferrugineum (sometimes called alpenrose, snow-rose, or rusty-leaved alpenrose) is an evergreen shrub that grows just above the tree line in the Alps, Pyrenees, Jura and northern Apennines, on acid soils.  It is the type species for the "Rhododendron" genus.  It may grow up to 1 m tall and produces clusters of pinkish-red, bell-shaped flowers throughout the summer.  The undersides of the leaves are covered in rust-brown spots, which give the species its scientific name.  This is in contrast to "Rhododendron hirsutum", which has no such brown colouring, has hairy edges to the leaves and grows over limestone.  Where the two species co-occur (usually on soils of intermediate pH), the hybrid "Rhododendron × intermedium" may occur; as its name suggests, it is intermediate in form between the two parental species.

Rhododendron minus: Rhododendron minus, the Piedmont rhododendron, is a rhododendron species native to Tennessee, North Carolina, South Carolina, Georgia, and Alabama.  It has two subspecies: "Rhododendron minus" var.  "chapmanii" and "Rhododendron minus" var.  "minus" (the latter also known as "Rhododendron carolinianum").

Rhododendron ponticum: Rhododendron ponticum, called common rhododendron or pontic rhododendron, is a species of "Rhododendron" native to southern Europe and southwest Asia.

Rhododendron maximum: Rhododendron maximum — its common names include great laurel, great rhododendron, rosebay rhododendron, American rhododendron and big rhododendron — is a species of "Rhododendron" native to the Appalachians of eastern North America, from Alabama north to coastal Nova Scotia.

Rhododendron subg. Rhododendron: Rhododendron" subgenus "Rhododendron is a subgenus of the genus "Rhododendron".  With around 400 species, it is the largest of the eight subgenera (more recently reduced to five) containing nearly half of all known species of "Rhododendron" and all of the lepidote (scales on the underside of the leaves) species.

Rhododendron macrophyllum: Rhododendron macrophyllum, the Pacific rhododendron, California rosebay, California rhododendron, coast rhododendron or big leaf rhododendron, is a large-leaved species of "Rhododendron" native to the Pacific Coast of North America.  It is the state flower of Washington.

Supporting paragraphs: Nothofagus Rhododendron
Answer: Rhododendron