Question: Which plant genus is native to South America, Astilbe or Phytolacca?

Context paragraphs:
Phytolacca dioica: Phytolacca dioica, commonly known as ombú, is a massive evergreen tree native to the Pampa of South America.  It has an umbrella-like canopy that spreads to a girth of 12 to 15 meters (40 to 50 feet) and can attain a height of 12 to 18 meters (40 to 60 feet).  Because it is derived from herbaceous ancestors, its trunk consists of anomalous secondary thickening rather than true wood.  As a result, the ombú grows fast but its wood is soft and spongy enough to be cut with a knife.  These properties have led it to be used in the art of bonsai, as it is easily manipulated to create the desired effect.  Since the sap is poisonous, the ombú is not grazed by cattle and is immune to locusts and other pests.  For similar reasons, the leaves are sometimes used as a laxative or purgant.  It is a symbol of Uruguay and Argentina, and of Gaucho culture, as its canopy is quite distinguishable from afar and provides comfort and shelter from sun and rain.

Conceveiba: Conceveiba is a plant genus of the family Euphorbiaceae, first described as a genus in 1775.  It is native to South America and Central America.

Actinostemon: Actinostemon is a plant genus of the family Euphorbiaceae first described as a genus in 1841.  It is native to South America, Central America, and the West Indies.

Adenophaedra: Adenophaedra is a plant genus of the family Euphorbiaceae first described as a genus in 1874.  It is native to tropical regions of South America and Central America.

Tibouchina: Tibouchina Aubl.  is a Neotropical flowering plant genus in Melastomataceae Juss.  that contains approximately 240 species.  Species of this genus are herbs, shrubs or trees and typically have purple flowers.  They are native to Mexico, the Caribbean, and South America where they are found as far south as northern Argentina.  Members of this genus are known as glory bushes, glory trees or princess flowers.  The name "Tibouchina" is adapted from a Guianan indigenous name for a member of this genus .  A recent systematic study has shown that this genus is paraphyletic.

Fischeria (plant): Fischeria is a plant genus in the family Apocynaceae, first described as a genus in 1813.  It is native to South America, Central America, southern Mexico, and the West Indies.

Caryodendron: Caryodendron is a plant genus of the family Euphorbiaceae first described as a genus in 1860.  The genus includes "C. orinocense", known as the Inchi tree or Tacay nut.  It is native to Central America and South America.

Hebe (plant): Hebe is a genus of plants native to New Zealand, Rapa in French Polynesia, the Falkland Islands, and South America.  It includes about 90 species and is the largest plant genus in New Zealand.  Apart from "H. rapensis" (endemic to Rapa), all species occur in New Zealand.  This includes the two species, "H. salicifolia" and "H. elliptica", that have distributions extending to South America.  The genus is named after the Greek goddess of youth, Hebe.

Phytolacca: Phytolacca is a genus of perennial plants native to North America, South America, East Asia and New Zealand.  Some members of the genus are known as pokeweeds or similar names such as pokebush, pokeberry, pokeroot or poke sallet.  Other names for species of "Phytolacca" include inkberry and ombú.  The generic name is derived from the Greek word φυτόν ("phyton"), meaning "plant," and the Latin word "lacca", a red dye.  Phytolaccatoxin and phytolaccigenin are present in many species which are poisonous to mammals if not cooked properly.  However, the berries are eaten by birds, which are not affected by the toxin because the small seeds with very hard outer shells remain intact in the digestive system and are eliminated whole.

Astilbe: Astilbe is a genus of 18 species of rhizomatous flowering plants within the family Saxifragaceae, native to mountain ravines and woodlands in Asia and North America.  Some species are known by the common names false goat's beard and false spirea.

Supporting paragraphs: Astilbe Phytolacca
Answer: Phytolacca