Art. LIV.—Notice of the Occurrence of a Variety of Zostera nana, Roth, in New Zealand.
[Read before the Wellington Philosophical Society, 12th January, 1878.]
Until within the last twenty years few groups of plants have received less attention than the Marine Phanerogams, all the known species of which belong to the Monocotyledonous Orders Hydrocharidaceœ and Naiadaceœ. A complete list by Dr. Ascherson, of Berlin, appeared in 1874 in Neumayer's “Anleitung in Wissenschaftlichen Beobachtungen auf Reisen,” containing twenty-six species arranged under eight genera.* The earliest record of any species having been found in New Zealand bears date so recently as 1867, when a Zostera, found in a flowerless condition in many places in the colony, was recorded in the “Handbook of the New Zealand Flora” as Zostera marina, L.—a species of wide distribution in the northern hemisphere—but the identity of our plant must be considered uncertain in the absence of flowers. I have now to record the discovery, in a flowering condition, of a second species, which, notwithstanding a slight departure from the normal characters, I identify with Zostera nana, Roth, and of which the following is a description.
Zostera nana, Roth, var. muelleri.
Z. muelleri, Irmisch.
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Stem creeping, rather stout for the size of the plant, clothed with the dead bases of old leaves. Leaves linear, 3–6 inches long, 1/16–1/12 inch wide, with about six nerves on each side of a midrib formed of two nerves in contact for their whole length, margin thickened; spathes 1–4, including the leafy portion 2–3 inches long, peduncles short, flattened; spadix rarely exceeding ¾ inch in length with inflexed membranous appendages on the margins; anthers about six on each side, ovules four; stigmas frequently exserted. Fruit faintly furrowed when mature.
Hab. North Island—Port Nicholson; on mud flats exposed at low water.
Our plant differs from the typical form in its more robust stem, clothed with the persistent bases of old leaves, leaves somewhat crowded and narrower, in the short, flattened peduncles, and in the rather larger fruit which agrees with the type in being faintly striated.
In Port Nicholson it is associated with the larger plant provisionally identified with Z. marina, the inflorescence of which must be sought in deep water.
[Footnote] * Not including Ruppia and those forms of Zannichellia and Potamogeton found in salt-water lagoons.
According to Dr. Ascherson, the typical form Z. nana has a wide distribution, occurring at the Canary Islands, Mediterranean, North Coast of Sicily, Smyrna, Black Sea, Caspian Sea, Portugal, Spain, France, British Islands, Holland, Denmark, Holstein, Japan, Cape of Good Hope, Port Natal, Nossi Beh.
Var. muelleri has been collected on the coasts of Chili, South and East Australia, Tasmania, and New Zealand.
Zostera tasmanica, G. v. Martens, is said to occur in New Zealand, but I do not know by whom collected. The plant intended is probably that referred to in the early part of this paper as Z. marina; but in any case the identification cannot be considered satisfactory in the absence of flowers, since it is possible that our plant may belong to Phucagrostis, which it closely resembles in habit.