Question: Buxus and Hydrocotyle umbellata can be both found on what continent?

Context paragraphs:
Hydrocotyle umbellata: Hydrocotyle umbellata, is an aquatic plant that thrives in wet, sandy habitat.  Its English common name is manyflower marshpennywort or dollarweed.  It is native to North America and parts of South America.  It can also be found growing as an introduced species and sometimes a noxious weed on other continents.  It is an edible weed that can be used in salads or as a pot herb.

Cyclobuxine: Cyclobuxine is an alkaloid, which can be found in "Buxus sempervirens" (family "Buxaceae") better known as common boxwood, and is derived from the cholesterol skeleton.  Alkaloids can be found in the whole plant, but the largest amounts of alkaloids (up to 3%) including cyclobuxine can be found in the leaves and bark.

Hydrocotyle javanica: Hydrocotyle javanica, commonly known as Java pennywort, is a species of "Hydrocotyle".  It is a prostrate herb found in NE India and SE Asia.  Leaves are simple, circular-heart-shaped, with seven triangular shallow lobes.  Leaves are 2.5-5 x 3-5.5 cm in size, and the margin has rounded teeth.  Java pennywort is closely related to Indian pennywort.  Tiny white flowers arise in 20 flowered umbels.  Java pennywort is seen in shady, moist places at altitudes greater than 1300 m. Flowers have five greenish-white petals and five stamens.  Fruit is broadly ovoid, 1 mm, laterally compressed.  In Manipur, the leaves are eaten as a substitute for Indian pennywort.  Flowering: June-July.

Climate of Africa: Due to Africa's position across equatorial and subtropical latitudes in both the northern and southern hemisphere, several different climate types can be found on the continent of Africa.  Africa mainly lies within the intertropical zone between the Tropic of Cancer and the Tropic of Capricorn.  Only the northernmost and the southernmost fringes of the continent have a Mediterranean climate.  Because of this geographical situation, Africa is a hot continent as the solar radiation intensity is always high.  Thus, warm and hot climates prevails all over Africa but the northern part is the most marked part by aridity and high temperatures.  The climate of Africa is a range of climates such as the equatorial climate, the tropical wet and dry climate, the tropical monsoon climate, the semi-desert climate (semi-arid), the desert climate (hyper-arid and arid), the subtropical highland climate etc.  Temperate climates remain rare through the continent except at very high elevations and along the fringes.  In fact, the climate of Africa is more dependent to rainfall amount than to temperatures as they are consistently high.  African deserts are the sunniest and the driest parts of the continent due to the prevailing presence of the subtropical ridge with subsiding, hot, dry air masses.  Africa holds many heat-related records : the continent has the hottest extended region year-round, the areas with the hottest summer climate, the highest sunshine duration etc.

Aethalopteryx diksami: Aethalopteryx diksami is a moth in the Cossidae family.  It is found in Socotra, Yemen, where it is only known from the central part of Socotra Island from two valleys: the Diksam canyon and the Difarroha valley, which are characterized by the following relict woody vegetation: "Dracaena cinnabari", "Buxus hildebrandtii", "Croton socotranus" and numerous other endemic plants.

Buxus: Buxus is a genus of about 70 species in the family Buxaceae.  Common names include box (majority of English-speaking countries) or boxwood (North America).

Hydrocotyle verticillata: Hydrocotyle verticillata, also known as whorled pennywort, whorled marshpennywort or shield pennywort, is a flowering plant found in South and North America and the West Indies.  The creeping plants with unusual leaves give it its common names.  It grows in places that are marshy, boggy, and wet. <br> "Hydrocotyle verticillata" is used in aquaria, where it is undemanding but prefers a good substrate, and at least moderate light.  It benefits from additional carbon dioxide.  It is widely used as a foreground plant.

Buxus macowanii: Buxus macowanii, aka Cape box, is an evergreen species of boxwood endemic to South Africa, where it occurs in two disjunct populations - in coastal forest and shady ravines from the Eastern Cape to southern Natal, and in the Waterberg of the central Transvaal.  The genus "Buxus", comprising more than 100 species, is found worldwide, but is absent from Australia.

Diospyros buxifolia: Diospyros buxifolia is a tree in the Ebenaceae family.  It grows up to 30 m tall.  Inflorescences bear up to five flowers.  The fruits are ellipsoid, up to 1.6 cm long.  The specific epithet "buxifolia " is from the Latin, referring to the leaves' resemblance to those of the genus "Buxus".  Habitat is forests from sea-level to 1000 m altitude.  "D. buxifolia" is found widely from India to Indochina and in Malesia as far as New Guinea.

Buxus obtusifolia: Buxus obtusifolia is a species of plant in the Buxaceae family.  It is found in Kenya and Tanzania.

Supporting paragraphs: Buxus Hydrocotyle umbellata
Answer: North America