''Pherosphaera hookeriana'', or Mount Mawson pine (previously known as ''Microstrobos niphophilus''), is a dwarf
conifer endemic to
Tasmania
)
, nickname =
, image_map = Tasmania in Australia.svg
, map_caption = Location of Tasmania in AustraliaCoordinates:
, subdivision_type = Country
, subdi ...
, at altitudes above 600 meters. There are roughly 30 known sites, with population numbers in the tens of thousands. The species occurs in a range of
habitats typically in areas near water bodies, mostly on
dolerite
Diabase (), also called dolerite () or microgabbro,
is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grain ...
derived
soils
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ter ...
. The species is highly fire sensitive and an increase in fire events associated with
climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
may lead to local
extinction
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
and fragmentation of habitat.
Description
''Pherosphaera hookeriana'' is a densely-branched erect
shrub or small
tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
growing to heights of 5 meters, branches are often small and rigid with leaves arranged spirally and fully
appressed
This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...
to the stem. Individual leaves can measure up to 1.5 mm long, and 1 mm wide, leaves are thick, blunt and concave with a rounded
keel
The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in Br ...
.
Male flowers form in compressed, terminal globular
cones
A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex.
A cone is formed by a set of line segments, half-lines, or lines conn ...
, ranging from 1–5 mm in diameter, with 8 to 15 fertile scales, each scale has two
pollen sacs on the
abaxial surface.
Female flowers occur in cones on short branches that usually droop (hence the old common name). The flowers are globular, 2–4 mm long and have 3-8 fertile scales, with a single ovule on the upper surface of each. When the
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
is ripe it has a hard,
glossy
Gloss is an optical property which indicates how well a surface reflects light in a specular (mirror-like) direction. It is one of the important parameters that are used to describe the visual appearance of an object. The factors that affect glo ...
brown coat and is approximately 1 mm in diameter (Curtis & Morris 1975, Hill 1998).
Identification and ecology
''Pherosphaera hookeriana'' is a dwarf conifer that has been recorded to grow up to 5 meters, but in exposed and harsh environments it may only attain a height of 0.5 meters (Minchin 1983). The foliage of ''Pherosphaera hookeriana'' is well adapted to the high altitudinal ranges it occupies, with small imbricate scale leaves, the
stomata are restricted to the