Question: What are both Hippophae and Ceratophyllum?

Context articles: Ceratophyllum muricatum
Hippophae
Hippophae rhamnoides
Leucocyanidin
Ceratophyllum
Montsechia
Ceratophyllum submersum
Sea buckthorn oil
Ceratophyllum echinatum
Ceratophyllum demersum

Ceratophyllum muricatum, commonly known as the prickly hornwort, is a species of "Ceratophyllum" native to much of Europe, Asia and Africa and been introduced elsewhere.
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.
Hippophae rhamnoides, also known as common sea buckthorn is a species of flowering plant in the family Elaeagnaceae, native to the cold-temperate regions of Europe and Asia.
 It is a spiny deciduous shrub.
 The plant is used in the food and cosmetic industry, in traditional medicine, as animal fodder and for ecological purposes.
Leucocyanidin is a colorless chemical compound related to leucoanthocyanidins. Leucoyanidin can be found in "Aesculus hippocastanum" (Horse chestnut), "Anacardium occidentale" (Cashew, acajou), "Arachis hypogaea" (Earth Nut), "Areca catechu" (Areca nut), "Asimina triloba" (American custardapple), "Cerasus vulgaris" (Cherry), "Cinnamomum camphora" (Camphor), "Erythroxylon coca" (coca), "Gleditsia triacanthos" (Honey locust), "Hamamelis virginiana" (American Witch Hazel), "Hippophae rhamnoides" (Hippophae berry Sanddorn), "Hordeum vulgare" (Barley), "Humulus lupulus" (bine), "Hypericum perforatum" (perikon Amber), "Laurus nobilis", "Magnolia denudata" (Hsin-I Yulan-Magnolie), "Malva silvestris" (Blue mallow), "Musa acuminata × balbisiana" (Banana), "Nelumbo nucifera" (Baladi bean), "Pinus strobus" (Eastern white pine), "Prunus serotina" ssp.
 serotina (black cherry), "Psidium guajava" (Common guava), "Quercus alba" (White oak), "Quercus robur" (Common oak), "Rumex hymenosepalus" (Arizona dock), "Schinus terebinthifolius" (Brazilian pepper tree), "Terminalia arjuna" (arjun), "Terminalia catappa" (Indian almond), "Theobroma cacao" (Cacao), "Drimia maritima" (Sea Squill), "Vicia faba" (bell-bean), "Vitis vinifera" (Common Grape Vine), "Zea Mays" (Corn, mais), "Ziziphus jujuba" (jujube, Chinese date).
Ceratophyllum is a cosmopolitan genus of flowering plants including four accepted species in 2016, commonly found in ponds, marshes, and quiet streams in tropical and in temperate regions.
 It is the only genus in the family Ceratophyllaceae, itself the only family in the order Ceratophyllales.
 They are usually called coontails or hornworts, although hornwort is also used for unrelated plants of the division Anthocerotophyta.
Montsechia is an extinct genus of aquatic plants containing the species Montsechia vidalii, discovered in Spain.
 "Montsechia vidalii" lived about 130 million years ago, during the Barremian age, and appears to be the earliest known flowering plant.
 It has affinities with the modern genus "Ceratophyllum".
Ceratophyllum submersum, commonly known as the soft hornwort, is a species of "Ceratophyllum".
 It is a submerged, free-floating aquatic plant.
 It has been reported from Europe, Central Asia, northern Africa, scattered places in tropical Africa, Turkey, Oman, Florida, and the Dominican Republic.
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.
Ceratophyllum echinatum, commonly called spineless hornwort, is an aquatic perennial plant of the genus Ceratophyllum.
 It can be found in ponds and lakes.
 It is principally an eastern North American species and the only species of its genus endemic to North America.
Ceratophyllum demersum, commonly known as hornwort, rigid hornwort, coontail, or coon's tail, is a species of "Ceratophyllum".
 It is a submerged, free-floating aquatic plant, with a cosmopolitan distribution, native to all continents except Antarctica.
 It is a harmful introduced weed in New Zealand.
 It is also a popular aquarium plant.