CABOMBA OR "FISH GRASS" by H

CABOMBA OR "FISH GRASS" by H. C. D. de WIT One of the most attractive indifferent as regards the soil in aquarium plants is generally called which they are rooting, they re "fish grass" (or also "fanwort"). quire soft water, of a decidely low This plant occurs wild in the east mineral content, to thrive. ern United States, as far north as The small cup-shaped flowers New York but it seems that, are also charming. They resemble actually, its natural home is not dwarf water-lilies which may have further north than the northeastern been one of the main reasons for border of Virginia. Its occurrence placing them in the family of the beyond that boundary seems to be water-lillies, N ymphaeaceae. Now due to introduction by man. adays it is often felt that Cabomba If grown successfully, fish grass ought to be accepted as represent or Cabomba caroliniana is a most ing a separate family, Cabomba beautiful plant in the aquarium by ceae, a view which is endorsed by its display of elegantly spreading the present author. garlands. Cabomba plants dis Flowering stems increase in size charge much oxygen into the water near the top and become spongy. which is another reason for its value They remain submersed but small as an aquarium plant. Cabomba floating leaves appear which are caroliniana with its small white or entire and widely differ in shape yellowish flowers is the only North from the normal foliage (see figure American species. In Central and 1, 2). In the axils of the upper South America, however, there are leaves the stemmed flowers appear several more, all of them very and are borne above the surface of valuable for the aquarist. It should the water. The three sepals (fig. be realized that Cabomba species 4) are greenish at first but assume are not among the easiest plants to the color of the three petals (fig. keep. 3) . The flower so appears to be The leaves are either opposite, six-leafed (fig. 1). In the flower in pairs, or arranged in whorls of two or three bristle-topped ovaries three. They are finely bisected but are present (fig. 5, 6) . if they are growing in shade or even A glistening drop of honey is if an abundant supply of light is often seen in the heart of the flow not available, the leaves will be er. Fig. 3 shows a petal: the dark considerably smaller and coarser, "earlets" or auricles carry the and the plant loses much of its minute glands secreting the nectar. beauty. Figure 7 and 8 show the After pollination has been effected upper and lower surface of the the flowering stem curves and the terminal forks of the leaf which, flower closes. The closed flower somewhat enlarged, appear to have (which sheds its petals and sepals spiny edges. only at a later stage) disappears Although Cabombas are rather (Continued on Page 88) 86 THE AQUARIUM Cabomba piauhyensis Gardner - 1: flowering stem, showing emerse and submerse leaves; 2: C. piauhyensis Gardn. f. albida Fass., the white-flowered Cuban form; 3: petal; 4: sepal; 5: stamens (one re moved) and ovaries in a young flower; 6: ovary, opened to show the pendent ovules; 7, 8: leaf-tips, enlarged, upper and lower surface. FEBRUARY 15 - MARCH 15, 1961 87 CABOMBA pulcherrima, would occur in the (Continued from Page 86) United States. Actually, I believe that Fassett was right in ascribing below the surface of the water two species of Cabomba to the where eventually the fruits may de- United States of America, the first velop. · being Cabomba caroliniana Gray It is not difficult to raise Ca a~d the second Cabomba pulcher bomba from seeds, but in practice rima, as Fassett named it. Al it is much simpler to use four or though I agree that two North five inches of a stem and make it American species of Cabomba produce roots by pressing it into exist, I am not convinced, how the soil. ever, that this second species should be named "Cabomba pulcherrima". ~he figure accompanying this I believe that so-called Cabomba article shows Cabomba piauhyensis pulcherrima is the same species as Gardn. It is perhaps the· most Cabomba piauhyensis, which would beautiful of all Cabombas and oc occur, then, from northern Brazil curs, it seems, in northern Brazil to South Carolina. Much depends up to Cuba and El Salvador. The on the variability of the distinguish flowers are deep purple and-yellow ing characters, and I feel that towards the center. A white or al growing the species of Cabomba most white (a slight ·purple tinge under close observation and in vari may be noticed) flowering form ous environments will do much to occurs in Cuba. The foliage of this clarify the natural limits between form is finer than in the continental the Cabombas. species. As regards its systematic posi This is another good subject for tion there is a comparatively recent study by plant amateurs among study by the late Norman ·c. Fas aquarists. sett, published in 1953. Fassett r~cognized purple Cabomba piauhyensis (and its white flowered Cuban form) as a well distinguish ed species. He referred also to a CORRECTION variety of Cabomba caroliniana On page 7 of the January issue of which was first described as "var. this year the fish captioned as Deep p~lcher~ima" and proposed to raise water Jack-knife fish should have read this variety to the rank of a species as follows: which ought to be called Cabomb~ pul_cherrima Harper (Fassett). Common Jack-knife Fish (Eques This latter, also purple-flowered, lanceolatus), shown here for com Cabomba then would occur in parative purposes. This species South Carolina, south-western often appears in marine aquarist's Georgia and adjacent Florida. I collections as it is frequently offered would not mention this debatable for sale and is far more accessible matter of systematics were it not than its aloof relative, Equetus that, if Fassett was right, a second punctatus, subject of this article. species of Cabomba, i.e. Cabomba 88 THE AQUARI U M .

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