Question: Are both Solandra and Petrophytum in a genus of plants in the rose family?

Context articles: Petrophytum cinerascens
Quillaja
Solandra
Petrophytum caespitosum
Malinae
Petrophytum
Hellebore
Horkelia
Sarcopoterium
Horkeliella

Petrophytum cinerascens (orth.
 var.
 "Petrophyton cinerascens") is a rare species of flowering plant in the rose family known by the common names halfshrub rockmat and Chelan rockmat.
 It is endemic to the state of Washington in the United States, where it occurs in just a few locations along the Columbia River in Chelan and Douglas Counties.
Quillaja is a genus of flowering plants, the only genus in the family Quillajaceae with two or three known species.
 It was once thought to be in the rose family, Rosaceae, but recent research shows it belongs in its own family.
 The inner bark of the soap bark tree ("Q. saponaria") contains saponin, which is a natural soap.
 Members of this genus are trees that grow to about 25 m .
Solandra is a genus of flowering plants in the nightshade family, Solanaceae.
 It is named after the Swedish naturalist Daniel C. Solander.
Petrophytum caespitosum (orth.
 var.
 Petrophyton caespitosum) is a species of flowering plant in the rose family known by the common name mat rock spiraea.
Malinae (incorrectly Pyrinae) is the name for the apple subtribe in the rose family, Rosaceae.
 This name is required by the International Code of Nomenclature for algae, fungi, and plants, which came into force in 2011 (article 19) for any group at the subtribe rank that includes the genus "Malus" but not either of the genera "Rosa" or "Amygdalus".
 The group includes a number of plants bearing commercially important fruits, such as apples and pears, while others are cultivated as ornamentals.
Petrophytum (orth.
 var.
 Petrophyton) is a small genus of plants in the rose family known as the rock spiraeas or rockmats.
 These are low mat-forming shrubs which send up erect stems bearing spike inflorescences of flowers.
 The brushy flowers are white and have many stamens and hairy, thready pistils. Rockmats are native to western North America.
Commonly known as hellebores , the Eurasian genus Helleborus consists of approximately 20 species of herbaceous or evergreen perennial flowering plants in the family Ranunculaceae, within which it gave its name to the tribe of Helleboreae.
 The scientific name "Helleborus" derives from the Greek name for "H. orientalis", ἑλλέβορος "helléboros", from "elein" "to injure" and βορά "borá" "food".
 Many species are poisonous.
 Despite names such as "winter rose", "Christmas rose" and "Lenten rose", hellebores are not closely related to the rose family (Rosaceae).
Horkelia is a genus of plants in the rose family.
 It includes several species of plants known commonly as horkelias.
 These are flowering plants closely related to the cinquefoils ("Potentilla") and sometimes considered part of the same genus.
 There are nineteen species found in western North America, especially California.
 "Horkelia" was named for German scientist Johann Horkel.
Sarcopoterium is a genus of flowering plants in the rose family.
 The genus is synonymous to "Poterium".
 The sole species within this genus, Sarcopoterium spinosum, is common to the southeast Mediterranean region and Middle East.
 It is a perennial bush with small flowers in inflorescence.
 "Sarcopoterium spinosum" flowers in February to April and its fruits mature in autumn, then fall to earth to germinate with the rain water.
Horkeliella is a small genus of two species of flowering plants in the rose family known as false horkelias.
 They are both endemic to California.
 These wildflowers were named after the genus "Horkelia" due to their resemblance, but are different enough to maintain a separate genus from the horkelias.
 They have leaves made up of small, overlapping, toothed leaflets and inflorescences of white or pinkish flowers which are similar in appearance to horkelias.