THE GRASSLANDS OF NEW ZEALAND.

New Zealand Journal of Agriculture, Volume XXVIII, Issue 2, 20 February 1924, Page 73

THE GRASSLANDS OF NEW ZEALAND.

{Continued.)

THE AGROSTIS SPECIES —RED-TOP, BROWN-TOP, AND CREEPING-BENT.

E. BRUCE LEVY,

Biological Laboratory, Wellington.

A | are few grasses of economic importance more puzzling in THERE and few grasses of economic importance more puzzling in form and character than those belonging to the genus Agrostis, and there are none perhaps over which a greater confusion exists at the present time in the mind of the farmer, the seed-merchant, the green-keeper, and even the specialized botanist. The names redtop,. brown-top, Waipu brown-top, florin, twitch, creeping-bent, carpetbent, velvet-bent, Agrostis alba, A. vulgaris, A. capillaris, A. canina, A. stolonifera, A. palustris, and A. tenuis have been variously applied and much confused. The present article has been prepared to clear up this confusion, and it also aims to deal fairly comprehensively with the . ecology and agricultural status of the Agrostis species as they occur in New Zealand.

There are three distinct and fairly easily recognizable agricultural species common in New Zealand, and in the naming of these the writer is keeping in accord with Piper,* Agrostologist, United States

Department of Agriculture. These three species are : (i) Red-top (Agrostis palustris), (2) brown-top, or colonial bent (Agrostis tenuis), and (3) creeping-bent {Agrostis stolonifera).

Other common and botanical names that have at times been applied to these species are —

(1.) Red-top (A. palustris) : A. alba of most botanists; florin of the seed trade; A. stolonifera of some merchants' catologues ; twitch. ,

(2.) Brown-top, or colonial bent (A. tenuis) : A. vulgaris of most botanists ; A. capillaris (of some American botanists) ; Waipu brown - top ' (of Auckland seed-growers and seed-merchants) ; twitch, or redtop (of Canterbury Plains and South Island generally) ; A. ' canina* (of some merchants’ catalogues) ; Rhode Island bent (of America).

(3.) Creeping-bent (A. stolonifera) : Carpet-bent (of American green-keepers) ; florin (of Dr. William Richardson, of Moy, Ireland) ; A. depressa and A. maritima (of some American botanists).

The species as above defined are by no means single entities. " At best all are big aggregates, each containing many puzzling forms. The aggregate species, however, are sufficiently clean-cut to be recognized in the field, and each is confined more or less to a definite habitat. The cause of ’variation within and between the species is extremely difficult to account for, but it would appear that hybridization played an important part, for it is in areas where the three species may be found together that one notes the greatest variation and often the most puzzling of forms. Again, where the habitat is such as to favour only the one species the growth-form and character of that species becomes more constant. Also, there is affinity between the aggregate - species. This affinity asserts itself not so much by a general similarity in the plants, but rather by a manifestation of special features such as ’ the appearance of the long rhizomes in otherwise short rootstock forms, or by the ready stolon development of otherwise non-stolon erect forms. These variations are distinct from habitat variations, which at times are extremely markedso much so that to" define the vegetative growth-form of the species botanically is almost' impossible. ■ •

From an agricultural point of view the three species mentioned above are economically and ecologically separate.and distinct. One is justified, therefore, from such point of view in accepting these three species, and it is hoped that the following descriptions and accompanying illustrations will serve to enable farmers and others to distinguish between them. In the main only macroscopic characters are illustrated —such as may be seen with the naked eye or with a lens magnifying up to ten diameters.

RED-TOP (AGROSTIS PALUSTRIS). General Description.

This is the strongest-growing grass of the three. In habit it is usually erect and somewhat stiff (Fig. 1). . The leaves are broad,

(All photos by

E. Bruce Levy.)

| in. wide in well-grown specimens, erect when young, drooping when older. The ligule*, is large, up to in. long, broad at the apex and often somewhat frayed, particularly on the older leaves (Fig. 2). The ligule of the uppermost leaf on the shoot is very conspicuous, encircling completely the succeeding young leaf while this is still rolled in the bud. The rootstock is stout, and long rhizomes (underground stems) are characteristic (Fig. 3). The rhizomes are many-noded, each node bearing roots, and a bud which may or may not develop. It is on account of these rhizomes that the name “ twitch ” has been applied to this grass by farmers on arable land. The tillering buds are stout and below ground. . The lower ones on the base of the vegetative shoot (crown) usually develop into rhizomes, while the upper ones may form new vegetative aerial shoots. The buds are generally few in - number, so that compact many-tillered shoots are rarely found in this species.

The rhizomes push slanting-wise downwards from the crown and extend along at a depth of some 1 in. to 3 in. in the soil, occasionally giving off shoots from buds along the rhizome. • More usually, however, the vegetative shoots are borne at the end of the rhizome, which turns up and projects through the ground maybe some 12 in. away from the parent plant. From these terminal . aerial shoots numerous roots are given off, which become the functional roots for the upward and seasonal growth of the aerial shoots. The crown of these shoots remains below ground. At first only a single shoot appears, which may or may not be supplemented later by other shoots. It is rather characteristic of red-top that the shoots appear at fairly widely spaced intervals, and that each crown bears only a few aerial shoots. Thus one seldom finds this species forming a dense close turf, but one that is usually very coarse and open. To green-keepers, bowlers, &c., it will be obvious, therefore, why redtop is undesirable as a lawn-grass.

The flower-head (panicle) is fairly characteristic —large, somewhat coarse, with the bran chiefs arranged in definite whorls. The primary branchlets are usually straight to the tip, and the two secondary branchlets coming off this about half-way along form a very narrow angle with it (Fig. 4). Before and after flowering the whorled appearance is very obvious, but during the flowering-period the branchlets are more widely disposed, expanding before and then compacting again after fertilization. The flowering-culm is tall, up to 30 in. high, and is usually erect, but dense growth may lodge somewhat. The aerial shoots scarcely ever give off branch shoots above ground.

Ecology and, Agricultural Status.

Red-top grows best in loose, damp, rather rich soils, but it will thrive and persist for many years on poorer, drier soils, particularly if such soils are periodically worked up with the plough. The growth-form of the plant almost demands a rather loose soil, for such soils give easy penetration to the rhizome, which is the only means

of vegetative spread that this grass has. So long, then, as the ground containing red-top is kept loose by working or by the peaty or loose nature of the soil it will persist for years, but so soon as consolidation is effected the growth becomes more stunted and the shoots become more sparse and slender; and if it is competing with a grass more at home on this consolidated soil the red-top almost invariablv- will be ousted from that soil. In New Zealand

many tons of red-top seed have been sown over a wide range of soils, but the grass to-day nowhere predominates in any old-established pastures. In waste places, particularly throughout peat-swamp lands, it may be frequently seen ; and on arable land it at times proves very' persistent, being there one of the worst twitch weeds. In these cases the loose nature of the soil is largely responsible for its persistence. '

On the hill country in Taranaki red-top sown years ago is still persisting, but the plants are poor and spindly and productive of very little feed. Its persistence at all there is due to the rather loose nature of the soil, the rather heavy rainfall, and the lack of competition of close turf-forming grasses. On the poorer, heavier, and more consolidated soil red-top will not persist in the permanent pasture. On these soils brown-top or danthonia are almost certain to replace the red-top. A good example of this recently came under the writer’s notice. Specimens from three fields near Masterton were received at the Laboratory for determination of species. Of these fields one was sown down twelve years ago with florin from Germany, and the other two were sown twenty-five years ago with red-top. All the specimens sent in were brown-top. Brown-top is a truly successional species on nearly all the good second-class soils of the Wairarapa, and red-top even if sown there would apparently go out in the course of time before the brown-top advance. This also will be very largely true of the heavier soils in New Zealand generally'■ ■those of Southland, the gum-lands of North Auckland, the heavy clays' of the Marton district, and those of the Wairarapa may be mentioned; but if these lands are worked and not allowed to consolidate, then the red-top will persist.

' Agriculturally red-top is of no significance in New Zealand, and in the writer’s opinion not a pound of seed of this grass should be imported into the country. It may have a place on certain wet, peat-swamp lands, but, generally speaking, better grasses may be successfully introduced there. • The seed is frequently used as a component of lawn-mixtures, but as a lawn-grass it ranks as one of the poorest. It may act as a quick cover for the first year or so, but perennial rye-grass would be much better for this purpose. ” Many grievous errors have been made by seed-merchants in contending that agriculturally red-top or florin is to all intents and purposes the same as brown-top, and . the former has been often supplied instead of browntop for hill-country sowings and for lawns.' A greater mistake than this could not be made ; red-top is practically useless on hill country or on lawns, whereas brown-top is one of the best grasses. The seeds of these two species certainly are alike, but the habits and growthform of the plants are essentially different. '

BROWN-TOP OR COLONIAL BENT (AGROSTIS TENUIS)

General Description.

Brown-top (Fig. 5) is a finer grass than red-top. In habit it is usually erect, but trailing shoots and slanting divergent shoots are quite a common feature, particularly in plants that have room to spread. In close-turf forms the shoots are mostly erect, and the closer the turf the finer the foliage. The leaves vary from extremely fine blades up to Jin. wide; they are erect when young, but come later to occupy a position almost at right angles to the. culm. The ligule is short (Fig. 6), scarcely ever exceeding in. long, and in the uppermost leaf hardly noticeably enfolding the succeeding young leaf while rolled up in the bud. Until one knows the plant by eye this short ligule is the best ready means of distinction in the vegetative

stage. The rootstock is more slender than in red-top, and long rhizomes are not characteristic when the grass is in the turf form (Fig. 7); but while the grass has room to spread, as in a newly worked field, then rhizomes up to 8 in. long may be formed. On account of these rhizomes, as in the case of red-top, the name “ twitch ” has been applied to this grass by farmers of arable land, particularly in the South Island As the ground becomes more consolidated so the length of the rhizome becomes shorter, until in a close turf they become merely short underground stems diverging somewhat from the last year’s crown. The tillering buds are borne on these short stems below the ground. When growth commences in the turf condition these buds develop into aerial shoots, almost erect from the crown, with' the result that a close turf is formed, and the closer and more numerous these shoots the finer does the turf become.

. The rhizomes when formed are. somewhat slender compared with those of red-top. They are many-noded, each node bearing roots and a bud, which bud may or may not develop. When these rhizomes are short, adopting really more or less the form of a widely divergent underground ■ tiller, it is usual for all the buds to develop into aerial shoots. On the other hand, if the soil conditions are loose certain of the buds develop into rhizomes. This rather emphasizes the close relationship of the aerial shoot to the rhizome, and the latter would appear to be a one-time aerial shoot that took to the earth to assist the plant in its colonization of light, free, and open soils, or possibly to avoid extinction during periods of drought. In the development of the rhizome red-top would seem to have' advanced beyond brown-top as regards this modification, so much so that if conditions are now made such that red-top cannot form these rhizomes the plant rapidly declines and goes out. Brown-top, on the other hand, thrives as well without the rhizome as it does with it, Just so long as the fertility of the soil is maintained. Again, in brown-top a very noticeable feature under somewhat shady conditions is the development of aerial shoots bearing lateral shoots. Such shoots undoubtedly will be the homologue of the rhizome.

In bro-top, also, there are frequently found trailing overground shoots which readily root at the nodes whenever these contact the soil, and from such rooting nodes there readily develops an aerial shoot. This character shows somewhat clearly an affinity of brown-top to the third species, creeping-bent. In growth-form, therefore, brown-top is essentially intermediate between red-top, on the one hand, and creepingbent on the other. As in the case of red-top, each rhizome or underground tiller forms shoots above ground singly at first, but this shoot is soon augmented in brown-top by numerous other shoots rising from the shoot-base (the crown) well below the soil-surface. Thus is formed a dense little tuft of many shoots. These each tiller further the next season, and there soon comes to be formed a dense turf of fine foliage. This dense tuif-forming attribute has made browntop one of the foremost grasses for all manner of playing-greens. To this attribute also is due its success as a bare-ground coverer and sward-former on agricultural (including pastoral) land, placing it as one of the best second-class grasses we have for steep hill country.

The flower-head (panicle) is characteristic, fairly large, outspreading and fine (Fig. 8). The branchlets are arranged in whorls, but are so disposed that to all intents and purposes 'the whorled arrangement does not appear as such. The . main-bran chief axis is not usually straight to the tip, but is divergent at an angle equal to that made by the secondary branchlets coming off it (Fig. 4). It is this more widely divergent arrangement of the secondary branchlets of the panicle that', destroys the whorled appearance. After flowering the

That on the left is in full bloom ; that on the right is closed somewhat after fertilization has taken place.

panicle may remain fine and open, particularly in warm sheltered spots, but usually the panicle closes up somewhat, especially if the weather is dry and windy at time of flowering (Fig. 8). The flowering-culm is fairly tall, but not so tall as in red-top (Fig. 9). The flowering-culms are numerous, and present a fine glossy shivery mass of bloom somewhat reddish-purple in colour. After flowering, however, the colour turns to a dull straw colour, and the whole stiffens somewhat in appearance.

Ecology and Agricultural Status.

Brown is by far the most common Agrostis species in New Zealand, and, agriculturally, it is the most important. Right throughout the country on all the rather heavy, better second-class soils brown-top is a truly natural successional species 2 succeeding to the better-class grasses and clovers (rye-grass, red clover, &c.) as these go out.. The writer looks upon the fact of brown-top growing well as an indication of average first-class short-rotational grassland soils. It marks soil on which perennial rye-grass will presist for about three years. Stiff heavy soils are the most suitable for brown-top, and the grass demands a good deal of. moisture — fact, the moisture factor is

more important than is the nature of the soil. Brown-top will persist on fairly light dry soils, but on the latter it is very inclined to dry out in the summer or to get sod-bound, so that the yield becomes very low.

The districts most suitable and where brown-top is most prevalent at the present time are the North Auckland better-class gum-lands, the. heavy soils of the Wairarapa, Manawatu, Westland, Southland, and north Otago, together with a belt running along the foothills of the Alps in Canterbury. The grass extends in altitude from sea-level up to 3,000 ft., being found in the Mount Cook region and on the volcanic plateau of the North Island. Higher-altitude forms, however, differ slightly from the lowland forms.

On ploughable country, excepting on the poorer second-class soils, brown-top is not looked upon with favour by the farmer as a good grazing proposition, and there is no doubt that it is inferior to the cocksfoot and crested-dogstail sward- which it is possible to maintain on these soils when ploughable. Brown-top growing well is a sure indication that the soil there is perfectly adapted for the cocksfoot, crested dogstail, and white clover type of pasture. It has been stated above that the fact of brown-top thriving indicates soil on which perennial rye-grass will last about three years—that is, under ordinary existing management of pastures. In the Department’s Bulletin No. 107* it is pointed out that there are four methods of grassing short-rotational grassland soils, one being by the transitional system (pp. 52-56). If certain species were included in the rye-grass pasture sowings under this system those pastures could remain more than three years and yet not run to weeds. The establishment of a very extensive market for brown-top seed in America, together with the fact that the grass itself is a good second-rate one, should make this system of grassing our better second-class soils more and more remunerative.

On third-class soils brown-top may be used to occupy the land tentatively —that is, until it is gradually replaced by certain other slowly establishing but more permanent species. Danthonia or paspalum, for instance, are extremely slow of establishment on poor country, and take a long time- to form a close sward. Brown-top if included in the mixture will hold such soils after the rye-grass, cocksfoot; &c., have run out and until the danthonia or the paspalum replace them.

As already mentioned, brown-top, like all turf-forming grasses, is inclined to become sod-bound, and the poorer and drier the soil the more quickly does this come about.f

For hill-country pastures where the rainfall is fairly high brown-top ranks as one of the most important grasses. Owing to its fine seed it establishes readily, and with its penetrating underground-stem systems it ramifies through pukahu and tree-fern stumps, &c., occupying those spots in the bush-burn where ordinarily it is extremely difficult to get other grasses to take ; and such spots, it must be remembered, are usually the places for the establishment of the fern-growth which proves so troublesome in the hill-country pastures. Brown-top on hill country really should occupy that grade of soil between the cocksfoot, crested dogstail, and white clover soil-type and the danthonia soil-type. All the Taranaki back-country, and the hill lands of the King-country, of North Auckland, of Westland, of Southland, and practically all moderately moist hill country in New Zealand, should have brown-top sown in addition to danthonia, and the better grassescocksfoot, crested dogstail, Poa pratensis, &c.

Brown-top is now becoming recognized as the most suitable of grasses for all manner of turfed playing-grounds, and practically all the brown-top seed sent out of New Zealand to America is used there in the formation of these greens. Up to the last few years it has been held that brown-top was confined to the North Auckland district, where the seed was harvested and sold under the name of Waipu brown-top. During the last three years the writer has made a very intensive study of the Agrostis species in New Zealand, and specimens have been collected * from all over New Zealand and grown at the Biological Laboratory alongside plants raised from type seed from America. It can now be said with certainty that brown-top is the common form of J gross's in. New Zealand, and that the form growing in the South ’ Island and other parts is identical with that growing in North Auckland. For lawns and playing-greens there is no doubt that brown-top is the grass •par excellence, producing as it does a very fine and . even turf, and being sufficiently hardy to stand the severe conditions of wear and close cutting that many greens are subject to.

It has been stated before that red - top is extremely poor as a lawn-grass, and in sowing down lawns care should always be taken to ensure that the brown-top seed used is free of • red-top. On heavy clays this is not so important, but on loose soils the red-top will persist and cause trouble by its rather stiffly erect shoots. Brown-top seed for export purposes should be entirely free of red-top.

CREEPING-BENT (AGROSTIS STOLONIFERA) .

General ' Description.

The characteristic feature of this grass is its long trailing overground stems (stolons) (Fig. io), which root at the nodes whenever these come into contact 'with the slighest moisture (Fig. n). From the rooted nodes an aerial erect shoot is given off. At the base of this shoot tillers may be formed, the lower ones at least of which will develop into the trailing, overground stems. Under close turf conditions the tendency to form long trailers is somewhat reduced, and then numerous’ rather fine erect shoots are formed, which under close grazing or close mowing form a dense turf. Just so soon, however, as the turf is allowed to get away the stolon habit reasserts itself, and there may be formed a dense .mat of intertwined stolons each sending up shoots at the nodes and forming a regular carpet. The American agrostologists have, in fact, in one publication called this grass the “ carpetgrass.” The rootstock and crown are entirely above ground, and there is no formation whatsoever of underground rhizomes.

The leaf is a trifle paler green in colour than that of brown-top, somewhat shorter and stout, tapering gradually from the base to the apex. On the older portion of the shoot the leaves are lax and somewhat drooping; towards the tip of the shoot they are stiffer and usually closely appressed towards the stem, thus forming with the latter a very narrow angle. The ligule is long and somewhat pointed, usually exceeding that of red-top in length, but being much narrower

and less frayed at the tip (Fig. 12). The ligule of the uppermost leaf is readily discernible, enfolding the young succeeding leaf while this is rolled up in the bud. This long white membranous ligule readily distinguishes creeping-bent from brown-top, and the growth-form resembles in no way that of red-top. The flowering-culm is scarcely ever strictly erect, being curved and kneed at the nodes. The panicle (Fig. 13) is usually short and smaller than that of red-top or browntop ; it is somewhat open when in flower, but readily compacting to a close almost spike-like form, the branchlets being compressed close in to the main axis or rachis of the panicle. . ,

Ecology and. Agricultural Status.

Creeping-bent is widely distributed throughout New Zealand, but agriculturally it is of minor importance only. Its habitat is very confined, the ideal situation for its greatest growth being in wet somewhat waterlogged soils. It is commonly found on hillsides bordering springs ; in fact, wherever the soil is moist at the surface for the greater portion of the year there will creeping-bent be found, providing that the vegetation in those spots is somewhat sparse and open.

, Creeping-bent will not compete successfully with other grasses that are stronger-growing and which form a fairly dense . cover. On the

richer portions of the Hauraki Plains, for example, it is the common grass on the roadsides, but through the fences inside the paddocks, where the rye-grass and meadow-foxtail type of pasture prevails, creeping-bent does not enter in to the pasture sward. ■ The grass will stand inundation of flood-waters for weeks at a time, and it grows freely in water up to 6 in. deep, but deeper submersion than this for any length of time will kill it. The grass associates at times with brown-top where this grass is thinned out somewhat . through being in situations a little too wet for its growth. Creeping-bent is also at times to be found in closely grazed damp pastures.

The herbage produced by creeping-bent is small in quantity and is not particularly palatable to stock. In Ireland Richardson commercialized this grass under the name of “ florin.” Seed could not be .obtained, but the grass was vegetatively distributed, the long trailing stolons being cut into short lengths. Each length containing a node will readily form a new plant when strewn on damp soil. Richardson claimed a great yield. from this grass on the bog-lands of Ireland, but in New Zealand the yield is never high, and, generally speaking, the soils that would produce big crops of creeping-bent here are. utilized for the production of more palatable grasses such as meadow-foxtail, Poa trivialis, timothy, &c.

The seed of creeping-bent has never been placed on the market, but German mixed bent, which is mainly brown-top, regularly contains about i per cent, of creeping-bent. Its presence in commercial lines enhances the value of German brown-top seed in the estimation of American green-keepers. The name “ florin ” has come to be associated with imported red-top by the seed trade. Formerly it was applied to seed from Germany, but now is more generally used for all imported red-top seed.

As a playing-green grass creeping-bent is very popular at the present time in America, .where putting-greens, &c., are laid down with it, the vegetative method of propagation being adopted. Under liberal top-dressings of soil and with a plentiful supply of water creeping-bent can be made to produce a very /fine and even turf. Without this attention, however, it is of no use as a fine playing-green grass. If the runners are allowed to form above ground a matted, uneven, and spongy turf is formed, which also readily dries out with hot. weather. The effect of soil top-dressing is to cover up any trailing stems, and so keep the crown below the surface. If this soil topdressing is not regularly done the grass becomes objectionable. As a general-purpose playing-green grass creeping-bent does not compare at all favourably with brown-top.

CONCLUSION.

The foregoing is a general classification of the Agrostis species in New Zealand. Each species is more or less an aggregate, in itself ecologically and economically distinct from the other two. There are many intermediate floristic forms, but to separate these would, the writer feels, further confuse the Agrostis position in New Zealand rather

than elucidate it. If in thfe future course of these grassland studies one form is met with that shows qualities above another, then it will be time enough to subdivide any one of the three existing well-defined aggregate species here dealt with.

(Series to be continued.)

* U.S. Department of Agriculture Bulletin No. 692, The Agricultural Species of Bent Grasses ; and personal correspondence. ,

* Agrostis canina (velvet-bent) is a fairly distinct species resembling in general growth-form creeping-bent (A. stolonifera). The plant is not . found growing in New Zealand under field conditions.

* The ligule is the white membraneous structure at the base of the leaf, and is of great value in grass-identification.

• . * The Grasslands of New Zealand, Series I, Principles of Pasture-establishment, by E. Bruce Levy. In future articles reference will often be made to this publication (a consolidation of articles which have appeared in the Journal}, and readers interested in these grassland articles should secure a copy from the Department of Agriculture, Wellington (price is.). f In a future series of articles on pasture-management the writer will deal with the problem of renovation of sod-bound pastures. >

* In the collecting of these Agrostis species the writer is indebted to several officers of the Fields Instruction Service for their assistance.