Question: Ostrya and Dracaena, are a genus of what?

Context paragraphs:
Dracaena braunii: Dracaena braunii is a species of the genus "Dracaena".  It is also known as "Dracaena sanderiana", after the German–English gardener Henry Frederick Conrad Sander (1847–1920).  Common names include Sander's dracaena, ribbon dracaena, lucky bamboo, curly bamboo, Chinese water bamboo, friendship bamboo, Goddess of Mercy plant, Belgian evergreen, and ribbon plant.  Although the word "bamboo" occurs in several of this plant's common names, "D. braunii" is of an entirely different taxonomic order from true bamboos. Despite several of its common names that suggest it is from China or Belgium, it is a native African species.

Ostrya carpinifolia: Ostrya carpinifolia, the European hop-hornbeam, is a tree in the family Betulaceae.  It is the only species of the genus "Ostrya" that is native to Europe.

Dracaena (lizard): The genus Dracaena (romanized form of the Ancient Greek δράκαινα - "drakaina", "female dragon"), also called caiman lizards or water tegu, is in the teiid family, along with tegus and ameivas.  Caiman lizards are found in South America in Ecuador, Colombia, Paraguay, Peru and Brazil.  These lizards spend a lot of time in the water and they inhabit marshes, streams and flooded forests.  Caiman lizards often bask on branches overhanging the water.

Dracophyllum: Dracophyllum is a genus of plants belonging to the family Ericaceae, formerly Epacridaceae.  There are some one hundred or so species in the genus, mostly shrubs but also cushion plants and trees, found in New Zealand, Australia and New Caledonia.  The name, "Dracophyllum" or dragon-leaf refers to their strong similarity to the unrelated "Dracaena", sometimes known as dragon tree.  Although dicotyledonous, they resemble primitive monocots with their slender leaves concentrated in clumps at the ends of the branches; they are sometimes called grass-trees.

Dracaena (plant): Dracaena ( , derived from the romanized form of the Ancient Greek δράκαινα – "drakaina", "female dragon", is a genus of about 120 species of trees and succulent shrubs.  In the APG III classification system, it is placed in the family Asparagaceae, subfamily Nolinoideae (formerly the family Ruscaceae).  It has also formerly been separated (sometimes with "Cordyline") into the family Dracaenaceae or placed in the Agavaceae (now Agavoideae).

Pseudovespicula dracaena: Pseudovespicula dracaena, the Draco Waspfish, is a species of waspfish native to the western Indian Ocean.  This species grows to a length of 7.5 cm TL.  This species is the only known member of its genus.

Ostrya: Ostrya is a genus of eight to 10 small deciduous trees belonging to the birch family Betulaceae.  Its common name is hophornbeam in American English and hop-hornbeam in British English.  It may also be called ironwood, a name shared with a number of other plants.

Pleomele (genus): Pleomele is a genus of flowering plants, sometimes placed in the genus "Dracaena".  In the APG III classification system, both genera are placed in the family Asparagaceae, subfamily Nolinoideae (formerly the family Ruscaceae).  The Hawaiian name for plants in this genus is hala pepe, which translates to crushed or dwarfed "Pandanus tectorius".

Entoleuca mammata: Entoleuca mammata is a species of fungus in the genus "Entoleuca".  It is responsible for the plant disease hypoxylon canker in hardwood trees such as quaking aspen ("Populus tremuloides") and other aspens and poplars, "Salix myrsinifolia" and other "willow" species, rowan ("Sorbus aucuparia"), Sitka alder ("Alnus viridis"), birch ("Betula spp.") , apple ("Malus spp.") , oak ("Quercus spp.") , and hophornbeam ("Ostrya spp.") .

Sansevieria: Sansevieria is a genus of about 70 species of flowering plants, native to Africa, Madagascar and southern Asia.  Common names include mother-in-law's tongue, devil's tongue, jinn's tongue, bow string hemp, snake plant and snake tongue.  It is often included in the genus "Dracaena"; in the APG III classification system, both genera are placed in the family Asparagaceae, subfamily Nolinoideae (formerly the family Ruscaceae).  It has also been placed in the former family Dracaenaceae.

Supporting paragraphs: Ostrya Dracaena (plant)
Answer: trees