PAMPAS GRASS AND ITS IDENTIFICATION.

New Zealand Journal of Agriculture, Volume 50, Issue 5, 20 May 1935, Page 274

PAMPAS GRASS AND ITS IDENTIFICATION.

H. H. Allan and V. D. Zotov,

Plant Research Station, Palmerston North.

Since the publication in this Journal (October, 1932, May, 1934) of articles by Mr. B. C. Aston on pampas grass as winter cow-feed, we have received numerous specimens from various localities with the inquiry whether they were specimens of pampas grass or not. In view of the economic importance of the grass it seems worth while giving a few details of its characteristic features, and of others likely to be confused with ittoetoe and Cunningham’s danthonia.

In the flowering stage these grasses are easily distinguished after a little careful examination. A glance at a flower-cluster of Cunningham’s danthonia (fig. 1) will show the features necessary

for comparison. The whole cluster (spikelet) has at the base two empty delicate husks (glumes). Above these are the florets, each on a short stalk (rachilla). In the drawing are shown four florets, surmounted by an imperfectly developed one, the spikelet being somewhat spread out to show the parts more clearly. The essential parts of each floret are enclosed between two husks. The larger outer one (lemma) enfolds the inner more delicate one (palea). In Cunningham’s dan th onia the lemma ends in two fine teeth, from between which extends a long slender bristle (awn). At the approach of flowering the upper portion of the palea is pushed out from the lemma and is seen to be sharply folded at each margin. The essential parts (male and female elements) are thus exposed to view. In Cunningham’s dan th onia (fig. 2) each floret contains both elements. The ovary (later ripening to form

the grain) is surmounted by two stalks (styles) each bearing a feathery pollen-catching apparatus (stigma). The male element consists of three stamens. A stamen consists of a stalk or filament carrying the pollen-containing anther. The figure shows an early stage of development, and for clearness only the filament of the front stamen is shown. With these points in mind the following key, along with the fuller descriptions given later, should enable any one to distinguish the three grasses here discussed. 1. Florets not obscured by very long hairs- 2. Florets obscured by very long hairs— —3. 2. Florets with both male and female \ elements ) (figs. I, 2, 4) Danthonia Cunninghamii. '• Florets containing male elements (stamens) only (fig. 3, d, e, f) — ACortaderia ar gentea. 3. Florets containing both male and female elements fully developed (fig. 5) Arundo cons-picua.

Florets containing only female elements fully developed (imperfectly developed stamens may be present) (fig. 3, a, b, c) Cortaderia ar gentea. All three plants form exceptionally large tussocks, with long coarse leaves and large inflorescences. In the absence of flowers the three species may readily be distinguished by . a careful examination of the leaf-structure. The leaf of a grass is in two main portions, a sheath clasping the stem, and a blade free from it. At the junction of the blade and the sheath there is usually a band somewhat differently coloured from the rest of the leaf (the collar), and on the inner face at the junction is also a structure known as the ligule. In our three grasses the ligule is a line of densely placed short hairs and does not serve as a good differentiating mark. But the arrangement of the veins is very distinct, as shown in the following key : — 1. Prominent stout veins run parallel to the midrib in both sheath and blade (fig. 6, b, e) Arundo conspicua. No prominent stout veins parallel to midrib ——2.

2. Sheath rounded, not showing a prominent midrib, but with numerous short cross veinlets (fig. 6, a, d) Cortaderia ar gentea. . . .. - ** “ Sheaths showing a prominent midrib, about which it is flattened ; cross veinlets not clearly visible (fig. 6, e, f)— — Danthonia Cunninghamii. ’

Pampas Grass.

The leaves of pampas grass {Cortaderia ar gentea) reach a length of 5 ft. or more, the lower part of the blade is erect; the upper

part turned through an . angle of 180 degrees. The sheaths ] are pale and somewhat brittle, with numerous fine veins connected,, [byshort cross veinlets, clearly visible when a portion of the sheath is held to the. light. The broad midrib of the blade does not extend into the sheath. Above the ligule on the inner face there is a . hairy portion, but this is much less developed than that found in toetoe. The blade is wider than that of toetoe, with numerous fine veins parallel to the midrib, but no development of especially stout lateral veins as in toetoe. On cutting across the sheath large air-spaces will be noted. The flower-stems are stout, solid, from 6 ft. to io ft. high, with erect feathery, silvery white or pinkish plumes, from i ft. to 3 ft. high, of densely placed spikelets. Each spikelet

(fig. 3, a, d) has two to three florets. On the female plants these florets (fig. 3, c) are clothed in long silky hairs, obscuring the lemmas, which terminate in a fine awn (not arising from between teeth as in toetoe and Cunningham’s danthonia). The male florets (fig. 3, f) lack the long silky hairs, and the white or brownish papery lemmas are clearly visible. The awn is as in the female floret.

't Pampas grass is a native of the country from Southern Brazil to Northern Argentina. It has long been known and grown as an ornamental grass; In America it is cultivated rather extensively, the plumes of the female plant finding a ready market in London, Berlin, New York, and other large cities. The forage aspect has been fully dealt with in Mr. Aston’s articles. The huge tussocks, with their densely crowded leaves, form a striking feature in landscape gardening, especially when in flower. It appears to have been first called pampas grass” in Paxton’s “ Flower Garden ” of 1850, but in its native haunts, Cortad&ria ar gentea is practically confined to watercourses, and to depressions where there is a constant supply of moisture. It is absent from the great grass areas known as the “ Pampas,” so. that the name is hardly appropriate, though now thoroughly established;

' In New Zealand it has been much used as an ornamental grass, and has in odd localities become more or less naturalized. It appears to be a shy seeder with us, partly owing to the sexes being on separate plants, so that a plantation increased by vegetative means may be all of One sex. As the female plant is much the more handsome there are . many more plants of this sex than of the male in gardens. I have no information whether one or the other sex is more favoured by stock, but certain strains may be more succulent than others.

Toetoe

Toetoe (Arundo-conspicua), a graceful indigenous grass, also forms huge tussocks; almost rivalling those of pampas grass. The leaves are almost as long, rather narrower, more finely toothed on the margins. The strong, straw-coloured side nerves form a very marked differential feature (in some forms the midrib and larger side nerves are distinctly reddened).- The sheaths are also nerved and much tougher than those of pampas grass, while the air spaces are smaller. The sheaths, too, when young, are covered by a bluish “ bloom ” absent in pampas grass. The flower-stems are up to 10 ft. high, more slender than those of pampas grass ; the plume is from 1 ft. to 2 ft. long, rather less dense, and usually somewhat nodding and of .a. yellowish to brownish tinge. This brownish tinge is more developed m the very closely related species Arundo fulvida: The teeth of the lemma are prolonged into awns (fig- 5; 5)-

This grass is distributed throughout New Zealand, often in large colonies. It favours swampy and damp ground, river-banks, and channels in the hillside. In some places it is also abundant on sanddunes. Stock do not greatly like the plant as it grows, but it has been found to be more or less readily eaten when cut or chaffed. In a small hillside paddock near Feilding, containing much toetoe and

some pampas grass, a few cattle were recently turned in. In a day or two the pampas grass was eaten to the ground, but the toetoe was hardly touched.

Cunningham’s Danthonia.

Cunningham’s danthonia [Danthonia Cunninghamn) is another handsome indigenous grass. It does not as a rule form such large tussocks as the other two species, though in certain river valleys in North-west Nelson stately examples may be met with. The leaves are from i ft. to 5 ft. long, much narrower than in the other two species. There

is a much sparser development of hairs near the ligule than in toetoe, and the blades and sheaths lack the stringy side veins of that species. There are usually scattered hairs on the margins of the blade in the lower portion, and the teeth are very fine. The flower-stems are from 2 ft. to 5 ft. tall, the plume about i ft. high as a rule, but occasionally much larger, and much more open and spreading, than in either pampas grass or toetoe, the spikelets standing apart on long slender stalks. The spikelets bear from three to seven flowers, and the hairs on the lemmas are short (fig. 4, 2), not concealing them. ,

This species is found through both Islands, but is absent from many areas. It is usually a montane grass, but in the South Island may be found along streams at low levels. Cattle and horses are fond of the plumes when these are in the early flowering stages.

For those possessing a lens and a sharp knife the shape and appearance of the cross-section of the blades will furnish a further means of distinguishing these grasses. Our sections (fig. 7) were taken from about the middle portion of representative blades. Heavy lines and darkened areas represent tough fibrous tissue. In such sections the differences of the venation are very clearly seen.