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It is TCi-y difiicult to decide upon the limits of species in this genus, which, like most aquatic plants, is sufficiently
Protean. My oini specimens are baiTen, but those of Dr. GiUies and Bridges, from the Andes and west coast of
South America, are iu flower and monoecious, and from them I have described the ripe carpels. Gaudichaud
distinguishes M. elatinoides from M. iematum, by the former being dioecious ; but D ’UrviUe, iu re-dcscribing it, asserts
the contrarj'.
In its normal state, the upper leaves of the present species are much broader than those of any other ; but at
times, the whole foliage is uniformly capillaceo-multifid, when it can hardly be discriminated from some forms
of the European M. verticillatum.
2. H IP PU R IS ,
1. H ip p u e is vulgaris, Linn. Sp. F l. 3. Engl. Bot. t. 763.
H a b. Strait of Magalhaens ; Po rt Eamine, Capt. King.
These specimeus, which are barren, do not seem to differ from others of European growth. Both Capt. King’s
and J lr. Anderson’s collections contain the plant, so that although the above be the only reported station for it in
the southern hemisphere, I have no reason to doubt its authenticity. The range of Hippuris vulgaris, in the
temperate latitudes of the northern parts of the world, is very wide, extending fi’om the arctic regions of Eui'ope and
Asia (Lapland 70°, Iceland 65°, Siberia and Kamschatka), south to JlontpeUier, lat. 43° in western Em-opc ; probably
reaching 50° in the central, and the Caucasus, or 44° iu the east parts of om* continent. The late Dr. Griffith
collected it in Affghanistan, lat. 32°, its only known habitat in Central Asia. In North America this species is
equally diffused, from the latitudes of 55° and 70° on the west coast, and from New York, 41°, to Labrador and
Greenland, lat. 70°, on the east. Prom the interior I have only seen specimens, gathered by Dr. Richardson near
Hudson’s Bay, between 55° and 60°.
Hippuris is very closely allied to Myriophyllum, and differs chiefly in the reduction of the fom* carpels to a
solitary one, with an accompanjing solitary stamen, placed on one side of the carpel, within the obsolete margin of
the caly-x.
3. CALLITRICHE, L .
1. Callitriche verna, L ., vid. FL Antarct. part i. p. 11. Antliapla, W.
Yslt. /S, terrestris ) PI. Antarct. 1. c.
Anderson in Bihl. Banks.
H a b. Puegia, the Falkland Islands, and Kerguelen’s Land, abundant; Anderson (in Cook’s 3rd Voyage),
•/. B . I I . Y^ar. Hermite Island and the Falkland Islands.
Callitriche differs from the typical genera of the Order Halorageæ in haring generally caducous bracts at
the base of the flowers, in its 4-carpellary ovarium with only two styles, in the enthe absence of a limb to the
calyx, of a corolla in the female, or of any perianth whatever in the male flower. The latter are truly achlamydeous,
but not the former, the calyx being equally obsolete in the carpels of Myriophyllum and in the present genus ;
whilst the general symmetiy of the parts, the structure of the seed and embryo, of the recmved styles, covered
uniformly with stigmatic papillæ, and the form of the pollen, are alike in both, indicating a very close natural
affinity. In the first part of this work, I alluded to the real form of the anthers in the southern specimens of
C. verna, as not differing from the ordinary structure of that organ in Phænogamic plants, even in appearance,
before their dehiscence, and only presenting the hippocrepiform suture on the curling up of the valves, and the
union of the two loculi and their lines of dehiscence above.
Callitriche verna is universally diffused thi-oughout the temperate regions of both hemispheres, even entering
I,
the tropics in the East Indies, and skirting the Ai'ctic oii-cle both in Europe, Asia, and America, In the south,
besides inhabiting aU the Antarctic Islands, it grows in New Zealand and Tasmania.
4. G U N N FEA , L .
1. G dnneba Chilensis, Lamk,, Enc. Méth. vol. iii. p. 61. Illu st. t. 801. f. 1. Brown et Bennett,
P la n t. la v . Bar. p t. 1. p. 70, G. scabra, B u iz et P a v . Fl. P e rm . vol. i. p. 29. t, 44. f. a. Ku n th Nov.
Gen. Am. vol. ii. p. 35. “ Panics," Feuill. Obs. ii. p. 741. t, 30.
IIa b . Clionos Ai'cliipelago ; C. Barwin, Esq.
Apparently the southern limit of a plant which is found along the whole eastern side of South Amenoa, from
Caraccas, in lot. 10° N.. whence we have specimens gathered by Mr. Pm-die, as far south as the 46th degree.
After the elaborate and learned essay upon tbis genus by 1Ù-. Bennett, in the ' Plantæ rariores Javæ,’ I have
little to remark upon its history or structure, except that the embi-yo is vei-y minute, heart-shaped, and placed at the
opposite extremity of the seed from the hilum, towards which the cotyledons point. The albumen is sm-ronnded
with a delicate testa and attached by a very short fiuiicidus to the osseous putamen, which (as Mi'. Bennett rightly
concludes) is derived from the inner coat ot the ovarium, and not, as Blume supposes, from the outer coat of
the seed.
Some years ago, after refen-ing a Tasmanian genus to Halorageoe, Mr. Brown had the kindness to direct my
attention to Gunnera, a plant closely allied to the one I was then examining ; this led to the remark contained
under the description of Milliijania in the ‘ leones Plantarum’ (t. ccxcix.) and the latter, probably, to Endlicber’s
removal of Gtmnera from Urticeoe. The correctness of this view of their affinity admits of no doubt, although the
alternate leaves separate Gunnera from all the genera of this order known to me.
The more obrious points of affinity between Gmmera and the Halorageoe proper, are the frequently unisexual
flowers, the qiiateniary an-angement of their pai-ts, the adherent tube of the calyx, the gi-eat similarity between the
two petals of Gimnera and Meioneetes, the form of the stamina and poUen-gi-ains, the styles covered throughout theii-
length with stigmatic papillæ, and the solitary pendulous albuminous seed. I may add the rigid and more or less
scabrid foliage, which is so conspicuous in Haloragis, the racemed and often pendulous flowers, and the frequently
long recm-ved styles.
The Gunneroe differ remarkably in having their leaves, as I mentioned above, alternate; the ovaria, though
furnished with two styles, are one-celled, with a solitaty ovule ; and the embryo, instead of being cylindrical and
axile, is very minute and placed at the opposite extremity of the seed from the Irilum, and it is also inverted, with
the radicle timied away from the hilmn. The stamens in Gtmnera are opposite the petals, and so are two of those of
Meioneetes. There is a tendency to irregularity in the form of the ovarium and its investing calyx, observable in some of
the plants of this group, and most evident in the foUoiring species and in Milligania, where fom* imeqnal teeth of the
calyx arc developed, tliis and the presence of two styles indicate that the ovarium is probably two-celled at a very early
period, one of which cells is suppressed. Lastly, in Milligania, a more intimate affinity is observable between
Gunneroe and Halorageoe, for there are frequently in that genus fom- erident styles united at the base into two,
indicating a normally four-celled ovai-imn, or one fomed of four caiqiellary leaves, placed like those of Callitriche,
in paii-s, but so intimately nnited as to appear more like the truly simple ovary of Hippuris.
Next to Halorageoe, Chlorantheoe is the order with which this genus has most in common, particularly through
the Sandwich Island gcnns Ascarina, of Forster, where the flowers are spiked or racemed and unisexual, the male
consisting of a solitary linear anther, sessile in the axil of a toothed bractea, and the female, when ripe, of a one-
cellcd drupe, very like that of Gunnera, surmoimted by a sessile obscurely 3-lobed stigma. The seed is compressed,
pendulous from the apex of the cell, covered with a delicate membranous testa; the albumen copious and oily,
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