Question: Which of the two plants, Macropidia or Hippophae, is the sole species of its kind?

Context articles: Nuclear Management Company
Cooperativa La Cruz Azul S.C.L.
Phaeosaccion
Macropidia
Sea buckthorn oil
Pyxidanthera
Gunnera tinctoria
Hippophae
Chambal Fertilisers
Selaginella selaginoides

Nuclear Management Company was a contract/operations firm that operated six nuclear power plants in the midwest US.
 NMC provided operational collaborations between plants.
 NMC did not own the plants, nor the energy produced from them.
 NMC's corporate headquarters were in Hudson, Wisconsin.
 As of September 2008 the operating licenses for the last two plants overseen by NMC, Monticello and Prairie Island, were transferred to Northern States Power Company (a wholly owned subsidiary of Xcel Energy), the owner of the plants.
 All personnel and assets of NMC were transferred to NSP, rendering NMC defunct.
La Sociedad Cooperativa Manufacturera de Cemento Portland La Cruz Azul, S.C.L. ("Blue Cross Portland Cement Manufacturing Cooperative Society") (C.S.L. means Co-operative Society Limited) is a Mexico-based construction industry solutions business.
 La Cruz Azul means in English "The Blue Cross" is an Enterprise with social responsibility and common endeavor source of four generations for over 80 years, have left an important legacy to the society in which it operates.
 It has four plants two are constituted as cooperatives and the other two established as limited companies with variable capital, called CYCNA (National Cement and Concrete).
 The two cooperatives are located in Ciudad Cooperativa Cruz Azul in Hidalgo and Lagunas in State of Oaxaca.
 The other two plants are located Tepezala in the state of Aguascalientes and Palmar de Bravo in the state of Puebla.
Phaeosaccion is a genus of brown algae with monostromatic tubular to saccate thalli, up to 20 cm long and to 2 cm wide.
 It is the sole genus in the family Phaeosaccionaceae.
 It is olive brown and resembles young plants of "Scytosiphon".
 The sole species in the genus is Phaeosaccion collinsii, a species of marine brown algae.
 It was first identified in a publication by W.G. Farlow in the article "Notes on New England algae" published in "Bulletin of the Torrey Botanical Club" in 1882.
 It was named in honor of Frank Shipley Collins.
Macropidia fuliginosa, the sole species of genus Macropidia, is a perennial rhizomatous flowering plant.
 Commonly known as the black kangaroo paw, it is endemic to Southwest Australia, specifically from Perth to Geraldton in the north of the region.
Sea buckthorn oil is derived from plants in a group of species of the genus "Hippophae", the most commonly used of which is "Hippophae rhamnoides".
 As species belonging to this genus accumulate lipids in the mesocarp (the fleshy part of the fruit), oil can be extracted from either the seeds or the pulp of the fruit.
 The resulting oil is used in cosmetics and skin care products.
Pyxidanthera is a genus of flowering plant in the family Diapensiaceae.
 The most widespread species, "Pyxidanthera barbulata", is native to the eastern United States, occurring on the coast from Long Island to New Jersey and Virginia to South Carolina.
 A second species of "Pyxidanthera" is widely recognized, called "Pyxidanthera brevifolia", known only from North and South Carolina.
 Some authors consider the two plants to be one species.
Gunnera tinctoria, known as giant rhubarb or Chilean rhubarb, is a flowering plant species native to southern Chile and neighbouring zones in Argentina.
 It is unrelated to rhubarb, as the two plants belong into different orders, but looks similar from a distance and has similar culinary uses.
 It is a large-leaved perennial plant that grows to more than two metres tall.
 It has been introduced to many parts of the world as an ornamental plant and in some countries (for instance New Zealand, Great Britain and Ireland) it has spread from gardens and is becoming a weed problem.
Hippophae is a genus of sea buckthorns, deciduous shrubs in the family Elaeagnaceae.
 The name sea buckthorn may be hyphenated to avoid confusion with the buckthorns ("Rhamnus", family Rhamnaceae).
 It is also referred to as sandthorn, sallowthorn, or seaberry.
Chambal Fertilisers and Chemicals Limited (Chambal) is one of the largest private sector fertilizer producers in India.
 It was promoted by Zuari Industries Limited in the year 1985.
 Its two hi-tech nitrogenous fertiliser (urea) plants are located at Gadepan in Kota district of Rajasthan.
 The two plants produce about 2 million MT of Urea per annum.
 The first plant was commissioned in 1993 and second plant in 1999.
 These plants use state-of-the-art technology from Denmark, Italy, United States and Japan.
Selaginella selaginoides is a non-flowering plant of the spikemoss genus "Selaginella" with a wide distribution around the Northern Hemisphere.
 It resembles a moss in appearance but is a vascular plant belonging to the division Lycopodiophyta.
 It has a number of common names including lesser clubmoss, club spikemoss, northern spikemoss, low spikemoss and prickly mountain-moss.
 This plant has one close relative, "Selaginella deflexa", native to Hawaii.
 These two plants form a small clade that is sister to all other "Selaginella" species.