User:Meikasnowy/sandbox/Hypopterygium dictyon (Umbrella Moss)

Hypopterygium dictyon (Umbrella Moss) Hypopterygium didictyon is a common rainforest and wet sclerophyll moss. Aptly named the umbrella moss, this species resembles miniature umbrella like structures on a dendroid or tree like growth pattern (Figure 1) [1].



Description and Structural Features
Umbrella moss displays two rows of asymmetrical leaves along the branch with a third row of smaller asymmetrical under leaves [1]. It has a liminal leaf and palmate or umbellate structure (Figure 2) [1].



These mosses are pleurocarp, with capsules located on a lateral branch as opposed to acrocarpous mosses, whose capsules are borne on the main stem [2]. Side branching in umbrella mosses gives it the carpet like appearance. In mosses, the capsule containing spores is borne on the end of a thin filamentous structure called a seta [3]. Most mosses have a ring of teeth at the mouth of the capsule, called peristome teeth, which can fold and unfold to release spores in response to changing levels of humidity [4]. Such peristomes are termed arthrodontous peristomes, being both jointed and toothed in umbrella mosses [4]. Umbrella mosses also have diplolepideous peristomes, with a double ring of peristome teeth, a further division of arthrodontous mosses [4]. Such features, and indeed the peristome itself, are vitally important for classification and identification of mosses to family, genus and species level [4].

Habitat
Occupying wet terrestrial bryophyte communities, umbrella mosses occupy the lower stratum, or levels, within a forest structure [5]. Umbrella moss location is largely dependent on availability of water, and is often found in humid forest and scrub woodlands, and around streams [3]. In addition, they are typically ground (terricolous) and rock (saxicolous) dwelling species, however favour lignocolous substrates, meaning they grow on dead and fallen trees within the forest (Figure 3) [3]. However importantly, this species is epiphytic, growing non-parasitically on the trunks of healthy living understorey and canopy trees in the forest, relying on air and rain for water [3]. Found on both smooth and papery barked trees, umbrella mosses grow on the trunks of a wide range of trees including of the following genus: Melaleuca, Leptospermum, Pomaderris, Nematolepsis, Acacia and Banksia [5].

Distribution
H. didictyon is found across South and South East Australia, including Victoria, Tasmania, New South Wales and South Australia (Figure 4) [3]. In Tasmania, this species occurs across most of the state, although is mostly absent in an area just North of the Great Western Tiers [3]. Elsewhere, this species is found across the North and South Islands of New Zealand, as well as the Chatham, Campbell, Auckland and Stewart Islands, and in Chile and Argentina [3].

Geographical variation
This species, and indeed the genus Hypopterygium displays considerable variable and plastic morphology, therefore significant physical differences exist between individuals exposed to different environmental influences [3]. In the past continental drift lead to fragmentation of populations and hence speciation events, this in turn has resulted in high levels of endemism in New Zealand, Australia and South America [3]. Large, more robust individuals occur only in Southern Chile and Southern New Zealand, where they are more dense and palmate in form [3]. In Northern New Zealand, individuals have a dwarfish stature, being more mat-like in form rather than the cushion-like form found elsewhere [3]. Australia has the least variation in plant size and shape [3].

Origin
The family Hypopterygiaceae is of Gondwanan origin, believed to have originated in East Gondwanaland [3].

Other Species in the genus Hypopterygium [3]
H. flavolimbatum

H. sandwicense

H. elatum

H. tamarisci

H. vriesei

H. discolor