''Euphorbia stygiana'' (

Portuguese Portuguese may refer to: * anything of, from, or related to the country and nation of Portugal ** Portuguese cuisine, traditional foods ** Portuguese language, a Romance language *** Portuguese dialects, variants of the Portuguese language ** Portu ...

: ''Trovisco-macho'') is a species of

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...

shrub in the family

Euphorbiaceae Euphorbiaceae, the spurge family, is a large family of flowering plants. In English, they are also commonly called euphorbias, which is also the name of a genus in the family. Most spurges, such as ''Euphorbia paralias'', are herbs, but some, e ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to several islands of the

Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...

. It has a critically endangered

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

(subsp. ''santamariae'') with only 20 known remaining mature individuals in the wild.

Description

''Euphorbia stygiana'' is an evergreen shrub with low but robust serpentine, green stems; white-veined, thick, leathery blue-dark green leaves and large yellow-green flower heads which are strongly honey-scented in spring and summer (from May to June). It can grow up to about tall in its native environment but is often tall and spreads to about wide. The leaves are long, slightly

pubescent The adjective pubescent may describe: * people or animals undergoing puberty * plants that are hairy, covered in trichomes * insects that are covered in setae In biology, setae (singular seta ; from the Latin word for "bristle") are any of a ...

on the bottom side. The fruits are , striated, subglobous and warty. During cold winters (especially outside its native range) these leaves may turn to a brilliant crimson colour. It is hardy down to

USDA The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of com ...

Zone 8b: to and can be propagated through stem cuttings.

Distribution and habitat

''Euphorbia stygiana'' is endemic to all Azorean islands except

Graciosa Graciosa Island () (literally "graceful" or "enchanting" in Portuguese) is referred to as the ''White Island'', the northernmost of the Central Group of islands in the Azores. The ovular Portuguese island has an area of , a length of and a width ...

where it inhabits the extremely humid highlands of the archipelago from in altitude, especially on

Pico Island Pico Island (''Ilha do Pico,'' ) is an island in the Central Group of the Portuguese Azores. The landscape features an eponymous volcano, Ponta do Pico, which is the highest mountain in Portugal, the Azores, and the highest elevation of the Mid ...

, in sheltered places such as ravines, craters and dense

laurel Laurel may refer to: Plants * Lauraceae, the laurel family * Laurel (plant), including a list of trees and plants known as laurel People * Laurel (given name), people with the given name * Laurel (surname), people with the surname * Laurel (mus ...

Juniperus Junipers are coniferous trees and shrubs in the genus ''Juniperus'' () of the cypress family Cupressaceae. Depending on the taxonomy, between 50 and 67 species of junipers are widely distributed throughout the Northern Hemisphere, from the Arcti ...

forests.

Subspecies

There are two known subspecies: *''subsp. santamariae'' – a critically endangered subspecies native only to the island of Santa Maria with less than 20 known mature individuals remaining in the wild, restricted to . The remaining population rests in a steep slope of a valley embedded in a stream, in a humid forest dominated by ''

Pittosporum undulatum ''Pittosporum undulatum'' is a fast-growing tree in the family Pittosporaceae. It is sometimes also known as sweet pittosporum, native daphne, Australian cheesewood, Victorian box or mock orange. ''P. undulatum'' has become invasive in parts ...

''. It is a smaller tree, and has a strong apical dominance. Foliage is less leathery with a faint bluish bloom. It also has a less pronounced

leaf vein A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...

and has fuzzy inflorescences with orange

extrafloral nectaries Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollination, pollinating animals, or by extrafloral nectaries, which provide a nutrient source to anim ...

. *''subsp. stygiana'' – the most common subspecies, inhabiting most of the Azorean islands except

and Santa Maria in high altitude, humid

forests.

Threats

The species is mainly threatened by agricultural development, change in land use, and invasive species and the subsequent increase in competition.

Toxicity

Like other members of the ''

Euphorbia ''Euphorbia'' is a very large and diverse genus of flowering plants, commonly called spurge, in the family Euphorbiaceae. "Euphorbia" is sometimes used in ordinary English to collectively refer to all members of Euphorbiaceae (in deference to t ...

'' genus, ''E. stygiana'' has a milky white

sap Sap is a fluid transported in xylem cells (vessel elements or tracheids) or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant. Sap is distinct from latex, resin, or cell sap; it is a separa ...

that may cause skin irritation or allergic reaction when in contact with the skin or eye. It is

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

if eaten.

Gallery

File:Euphorbia stygiana, Conservatoire botanique national de Brest 02.jpg, Specimen in the National Botanical Conservatory of Brest, France File:Euphorbia stygiana, Conservatoire botanique national de Brest 06.jpg, Closeup of fruit File:Euphorbia stygiana, Conservatoire botanique national de Brest 03.jpg File:Euphorbia stygiana, Conservatoire botanique national de Brest 01.jpg

References

External links

* Hooker's J. Bot. Kew Gard. Misc. 3: 605 1844.
The Plant List entry

Plant Database entry
{{Taxonbar, from=Q5410581 stygiana Endemic flora of the Azores