Art. XIX.—On the discovery of Isoëtes, and other genera of Rhizocarpæ, new to the Flora of New Zealand.
[Read before the Auckland Institute, October 18, 1869.]
During the past autumn I had the pleasure of making a short tour in the Waikato, in company with my friend Captain Hutton, specially with the object of searching for Rhizocarpæ, and other obscure aquatic plants. Although our explorations were abruptly stopped by heavy and continued rain, a portion of the results is of sufficient importance to warrant its being placed on record, even in a necessarily imperfect condition, in order to draw the attention of colonial botanists to genera not previously observed in New Zealand, but which will, in all probability, be ultimately found in every province.
Great attention has been paid to the Rhizocarpæ during the last twelve years, especially by Dr. Alexander Braun, of Berlin, and M. Gay, of Paris. At the commencement of that period only one species of Isoëtes was recognized, I. fluitans, L.; although it is not unlikely that the plant now known as I. echinos-pora, Dur., may have been the I. fluitans, var. gracilis, of authors, the differences at that time observed being confined to habit of growth, texture, etc. It is only within the last eight or nine years that the value of the macrospores, as affording specific characters, has been fully demonstrated. More than twenty species are known, of which five are Australasian.
Our Waikato Quillwort proves to be a new species, Isoëtes Kirkii, Braun, and is closely allied to the Tasmanian I. humilior, F. Muell. The leaves (fronds), are from 2–4 inches in length, rounded and very slender, in strong plants spreading; sporangium 4-celled; macrospores sexangular, with slightly-raised margins, finely punctate; microspores obscurely triangular, minutely punctate. The macrospores appear to vegetate, in many instances, before leaving the capsule, thus forming dense masses of slender pale-green leaves amongst the decaying leaves of older growth.
Other species may be expected to occur in our central and alpine lakes.
Pilularia, sp. Specimens with short solitary leaves, and small capsules, were discovered, but too far advanced to admit of identification.
? Marsilea, sp. A solitary specimen, in imperfect fruit, apparently resembling Marsilea pubescens, was collected, growing with another obscure plant, which may possibly prove to be referable to the Australian genus Microcarpæa, belonging to the Scrophulariads.
In addition to the above, an undescribed pondweed, allied to the European Potamogeton zosteroefolius, Schum., was collected, also Scirpus fluitans, L.
Isolepis fluitans, R. Br., (Eleogiton fluitans, Link), was discovered for the first time in the colony, and at least three species of Chara, not before recorded.
Of scarcely less interest was the occurrence of Zannichellia palustris, L., Ruppia maritima, L., Potamogeton pectinatus, L., and other plants, not pre-viously known to occur in the Province of Auckland, thus exhibiting a marked extension of their northern and western range.