Question: Which genus, Cymbopogon or Amherstia, has a larger native habitat?

Context paragraphs:
Cymbopogon martinii: Cymbopogon martinii is a species of grass in the genus "Cymbopogon" (lemongrasses) native to India and Indochina, but widely cultivated in many places for its aromatic oil.  It is best known by the common name palmarosa ("palm rose") as it smells sweet and rose-like.  Other common names include Indian geranium, gingergrass, rosha, and rosha grass.

Amherstia: Amherstia nobilis (Burmese: သော်ကကြီး ] ; the Pride of Burma, in the Fabaceae family) is a tropical tree with large, showy flowers.  It is the only member of the genus Amherstia.  It is widely cultivated for ornament in the humid tropics, but is very rare in the wild and has only been collected from its native habitat a few times.  It is native to Burma (Myanmar), hence the common name.  The scientific name commemorates Lady Amherst, (as does Lady Amherst's pheasant) and also her daughter Sarah.  Another common name, the Orchid Tree, is otherwise reserved for members of the genus "Bauhinia".

Centaurea cyanus: Centaurea cyanus, commonly known as cornflower or bachelor's button, is an annual flowering plant in the family Asteraceae, native to Europe.  In the past it often grew as a weed in cornfields (in the broad sense of the word "corn", referring to grains, such as wheat, barley, rye, or oats), hence its name.  It is now endangered in its native habitat by agricultural intensification, particularly over-use of herbicides, destroying its habitat.  It is also, however, through introduction as an ornamental plant in gardens and a seed contaminant in crop seeds, now naturalised in many other parts of the world, including North America and parts of Australia.

Centris pallida: Centris pallida is a species of solitary bee native to North America.  It lacks an accepted common name; however, it has been called the digger bee, the desert bee, and the pallid bee due to its actions, habitat, and color respectively.  The solitary nature of this bee allows for a dual-strategy mating system which produces an evolutionarily stable state resistant to invading strategies.  These bees have also evolved to withstand the high temperatures of their native habitat.  "C. pallida" routinely has internal temperatures within 3 degrees Celsius of death.

Sports teams named Redskins: Sports teams named "Redskins" are part of the larger Native American mascot controversy regarding the use of Native American names, images and symbols by non-native sports teams.  Teams of this name have received particular public attention due to the fact that the term "redskin" is now generally regarded as disparaging and offensive.

Echium pininana: Echium pininana, also called tree echium, pine echium and giant viper's-bugloss, is a plant, native to La Palma in the Canary Islands, that is now cultivated in gardens of Britain and Ireland.  Its native habitat is laurel forests, where it is now endangered through habitat loss.

Ambrosia cheiranthifolia: Ambrosia cheiranthifolia is a rare species of flowering plant known by the common names South Texas ambrosia and Rio Grande ragweed.  It is native to the coast of South Texas and the Mexican states of Tamaulipas and Coahuila.  It occurs in coastal prairie, grassland, and mesquite shrubland habitat.  It has declined because its native habitat has been cleared for development, with remaining open savanna invaded by non-native grasses such as buffelgrass ("Cenchrus ciliaris").  Today there are perhaps 20 populations remaining, but some of these may have very few genetic individuals because the species is clonal, with many cloned plants attached by one rhizome.  It is not certain that the plant still exists in Mexico.  This is a federally listed endangered species of the United States.

Cymbopogon flexuosus: Cymbopogon flexuosus, also called Cochin grass or Malabar grass, is a perennial grass native to India, Sri Lanka, Burma, and Thailand.  It is placed in the genus "Cymbopogon" (lemongrasses).

Cymbopogon: Cymbopogon, better known as lemongrass ( ; ), is a genus of Asian, African, Australian, and tropical island plants in the grass family.

Penstemon venustus: Penstemon venustus is a species of penstemon known by the common names Venus penstemon and alpine penstemon.  It is native to the northwestern United States, where it grows in many types of open habitat.  It is a spreading shrub growing erect to a maximum height near 80 centimeters.  The thick, stiff leaves are lance-shaped, serrated, and up to 12 centimeters in length.  The showy inflorescence bears many tubular lavender flowers, the largest nearly 4 centimeters long.  The mouth of the flower and the staminode are covered in long, white hairs.  This penstemon is cultivated for use in wilderness landscaping in its native habitat.

Supporting paragraphs: Cymbopogon Amherstia
Answer: Cymbopogon