Hypnodendron comosum

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Hypnodendron comosum
Scientific classification Edit this classification
Kingdom: Plantae
Division: Bryophyta
Class: Bryopsida
Subclass: Bryidae
Order: Hypnodendrales
Family: Hypnodendraceae
Genus: Hypnodendron
Species:
H. comosum
Binomial name
Hypnodendron comosum
(Labill.) Mitt.
Varieties

Hypnodendron comosum var. comosum
Hypnodendron comosum var. sieberi

Hypnodendron comosum, commonly known as palm moss or palm tree moss, is a ground moss which can be divided into two varieties: Hypnodendron comosum var. comosum and Hypnodendron comosum var. sieberi.

Victoria, and Tasmania in southern Australia and in New Zealand.[2][1][3]

This "miniature forest" dendroid species is viewed by David Meagher and Bruce Fuhrer in their publication A Field Guide to the Mosses and Allied Plants of Southern Australia as one of the most beautiful and unique species of mosses in the southern region of Australia.[4] While both varieties are extremely similar, they are easily identified by their elevation above other moss and lichen species within their ecosystem. Positioned atop an erect stem, the branches form an umbrella shape, the source of the common name "palm tree moss".[2][5][4]

Appearance

Hypnodendron comosum var.comosum (left) and Hypnodendron comosum var. sieberi (right)
Labeled features of Hypnodendron comosum var. sieberi

The appearance for both varieties is similar with both sharing many of the same features. Resembling the trunk of the tree, the stems are elongated and narrow growing between 2–9 cm (0.79–3.54 in) in length. They are black or brown in colour and covered in trichome hairs and small leaves. The stem reaches up to a green umbrella shaped arrangement of fronds at the top. The horizontally spreading

capsule is orange or brown in colour and reaches around 2–5 mm (0.079–0.197 in) in length. They are cylindrical in shape. The operculum is the cap or covering to the spores, and once this falls off, the spores are passively dispersed via the peristome.[2] While both species are similar, Hypnodendron comosum var. comosum is unique in that it is the smaller, more compact of the two. Most commonly located in Tasmania, its branches are compactly arranged, making this variety seem clumped and tightly packed. Located on mainland Australia, Hypnodendron comosum var. siberi is taller in form and the branches are much more loosely arranged.[2]

Physiology

Like all

rhizoids. Unlike vascular plants that use their roots to exchange gas and extract nutrients and water from the soil, bryophytes are able to do this over the leaf surface, depositing nutrients and water where they are required.[4][3]

Habitat

This image shows the filtered amounts of light, distribution and other communities of moss and the different levels of understory. This is a rainforest located in Tasmania.
Hypnodendron comosum community taken in Tasmania's wilderness

The plant is commonly located in wet forests and rainforests consisting of moist humeric layerings with loamy soil composition. Favouring wet rocks, tree roots, the base of live trees and tree ferns, it is most commonly located in areas with large amounts of decaying logs and decomposing matter.[2][1] This species forms clumps like colonizing patterns in dry conditions and, when conditions are moist, H. comosum forms small forest mats with large numbers, indicating wetter environments are preferable.[1][4]

Geographical distribution

Hypnodendron comosum is endemic to the Australian states of New South wales, Victoria, and Tasmania and to New Zealand,

Stuart Island, and the Campbell Islands.

Distribution of both varieties of Hypnodendron comosum, H. c. var. comosum and H. c. var. sieberi

Since it is located in New Zealand as well as Australia, this indicates that the species predates

Gondwanaland, suggesting that this species may be included as one of the earliest species to diverge from water to land and may give vital insight toward how vascular plants evolved.[2][1][3] Hypnodendron comosum var. sieberi is more commonly located on mainland Australia and the northern South Island of New Zealand, whereas H. c. var. comosum is more commonly located in Tasmania, the southern South Island of New Zealand, and the islands located in the southern ocean.[2]

Phylogeny

Phylogenetic tree of Hypnodendron comosum

Life cycle

Like all mosses, Hypnodendron comosum has an

archegonia with haploid sperm producing a diploid zygote. This zygote then divides via mitosis and forms the sporophyte.[3] The sporophyte stage is the spore-forming event of the lifecycle. Once the zygote has begun to enlarge, the seta elongates and develops a sporangium on the end in the form of a capsule. This capsule consists of sporogenous tissue, a peristome to regulate the dispersal of spores, and an operculum to protect early release.[3] Once spores are released, they germinate and grow into a narrow long rhizoid-like form named a protonema. This protonema develops buds which grow to become either a male or female gametophyte. The male gametophyte is named the antheridium and the female the archegonium. This is the gametophyte stage.[3]

References

  1. ^
    ISSN 0029-5035
    .
  2. ^ a b c d e f g h "Australian Mosses Online". Department of Agriculture, Water and the Environment. Retrieved 9 March 2014.
  3. ^
    ISBN 0-7167-1007-2.[page needed
    ]
  4. ^
    ISBN 978-0-642-56828-1.[page needed
    ]
  5. S2CID 86280908
    .
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