C. fulvida C. richardii C. toetoe C . splendens Species of Cortaderia (pampas grasses and toetoe) in New Zealand BARBARA KNOWLES AND CHRIS ECROYD FRI BULLETIN NO. 1 05 SPECIES OF CORTADERIA (PAMPAS GRASSES AND TOETOE) IN NEW ZEALAND Barbara Knowles and Chris Ecroyd This FRI Bulletin provides an identification guide to the species of Cortaderia in New Zealand to assist forestry personnel and others involved in the control of introduced pampas grasses and in the conservation and amenity use of native toetoe. FOREST RESEARCH INSTITUTE, NEW ZEALAND FOREST SERVICE PRIVATE BAG, ROTORUA, NEW ZEALAND 1985 ISSN 0111-8129 ODC 175.2 Cortaderia (931) CONTENTS PREFACE ( i} ABSTRACT 1 INTRODUCTION 1 THE GENUS COKI'JIDERIA 3 THE INTRODUCED SPECIES (PAMPAS GRASSES} 6 Cortaderia selloana (pampas grass} 6 Cortaderia jubata (purple pampas grass} 8 THE NATIVE SPECIES (TOETOE} 13 Cortaderia fulvida 14 Cortaderia richardii 14 Cortaderia toetoe 15 Cortaderia splendens 15 HYBRID ISM 15 DISCUSSION AND CONCLUSIONS 16 REFERENCES 17 APPENDIX 1 - KEY TO CORTJIDERIA IN NEW ZEALAND 20 APPENDIX 2 - TABLES SUMMARISING DIFFERENCES BETWEEN SPECIES 21 APPENDIX 3 - GLOSSARY OF TERMS 24 PREFACE This FRI Bulletin has been prepared primarily as a guide to the identification of cortaderia species (pampas grasses and toetoe} in New Zealand in order to assist in dealing with the serious forest weed problem caused by the introduced species and to help ensure the conservation of the native species. The current role of the introduced pampas grasses as forest weeds, which is dealt with in more detail in other publications, is also briefly discussed. This publication expands on information provided in What's New in Forest Research No. 128 (1984} and leads the reader to more detailed information in the literature. Much of the information contained in the text is summarised for quick reference in tables included in Appendix 2 of the publication. The information on which this publication is based has come from a wide variety of sources. We are indebted to Dr H. Connor (Centre for Resource Management, University of Canterbury} for information and comments on the text and particularly to Dr R. Gadgil (FRI) and also to Mr N. Percival (Ministry of Agriculture and Fisheries) for constructive criticism and helpful comments. Mr P. Hay (Forestry Training centre), Mr L. Knowles (FRI), and Dr J. Herbert (FRI) also provided useful comments on the manuscript. We are also very grateful to the following FRI personnel: Mr D. Kershaw for permission to use the species distribution map, the Forest Health Officers for specimens and information on distribution, Mr D. King for assistance with Fig. 2 and Fig. 3, Mr s. Burgess for preparation of the illustrations, and Mr H. Hemming, Mr J. Barran, and Mr J. Bain for the photographs. (ii) Species Infestation level Extreme High Light C. jubata C. selloana • • • C. jubata and C. selloana • • • ~ ... A •• o-. I 'J •• • • • A •• D. A • • • • As yet, no records of pampas in forests south of Nelson­ Marlborough MAP 1- MAP SHOWING THE RECORDED DISTRIBUTION OF PAMPAS GRASSES IN NEW ZEALAND'S EXOTIC FORESTS AND THE DEGREE OF INFESTATION ABSTRACT TWo pampas grasses from South America, cortaderia selloana and c. jubata, are serious weeds in some exotic forests in northern New Zealand. Descriptions, tables, a key, and photographs are provided to assist with the identification of these species and the native species of cortaderia - c. :ful vida, c. richardii, c. toe toe, and c. splendens, ·an commonly known as toe toe. KBnlORDS: Cortaderia :fulvida, Cortaderia jubata, Cortaderia richardii, Cortaderia selloana, Cortaderia splendens, cortaderia toetoe, pampas grasses, toetoe, New Zealand, identification, distribution, weeds. INTRODUCTION The recognition that pampas grasses are a serious and increasing weed problem in exotic forests near Auckland and Rotorua (Gadgil et al. 1984), with forests in other areas potentially at risk, has drawn considerable recent attention to the genus cortaderia in New Zealand. The problem is caused by the introduced south American species cortaderia selloana and c. jubata. Pampas grasses were first recognised as a problem in forests in the 1970s. Since the mid-1970s both species have spread dramatically in a number of forests north of Rotorua (Gadgil et al. 1984). By early 1984 approximately 12 500 ha in six state forests in Auckland Conservancy were classed as severely infested as indicated in What's New in Forest Research No. 128 (New Zealand Forest Service, Forest Research Institute 1984). Infestation levels were high to extreme in a total of 19 forests, 18 of them north of Rotorua; in addition, another 80 forests in the North Island and the top of South Island were classed as lightly infested [Map 1, p. (ii)]. Barely adequate release treatments were estimated to cost $350/ha in 1983 and one evaluation indicated an increase of 144\ in total tending costs for trees growing in dense pampas (Gadgil et al. 1984). In order to evaluate the existing and potential threat from these species it is highly desirable to identify them accurately at all stages of growth. Plants of the two species have proven difficult to distinguish when not flowering. In addition to these two south American species, there are four native species of cortaderia - commonly referred to as toetoe - in mainland New Zealand. It is important that the features distinguishing South American pampas grasses from the native toetoe be known and understood so that the native species can be protected from possible unwarranted destruction. The following descriptions provide a basis for determining the main points of difference between the species. Barbara Knowles (B.Sc.) and Chris Ecroyd (B.Sc. Hons.) of the Genetics and Tree Improvement Research Field at the Forest Research Institute are members of the Pampas Control Project, a multidisciplinary team set up to resolve the serious forest weed problem caused by the introduced species of Cortaderia. 2 FIG. 1- DIAGRAMMATIC REPRESENTATION OF FEATURES IN CORTADERIA flower head (panicle) hairs DETAIL OF SPIKELET mid rib DETAIL OF UPPER ADAXIAL) SURFACE OF LEAF SHOWING LIGULE 3 THE GENUS CORTADERIA cortaderia is a member of the grass subfamily Arundinoideae and comprises about 25 species (Connor 1983), distributed mainly in south America, but with four species in New Zealand and one species in New Guinea. In Central and south America it is restricted mainly to the mountainous regions where it grows up to 4000 m above sea level (Costas-Lippmann 1976). All the species in New Zealand have the following characteristics: 1. Habit: a dense perennial tussock (Plate 2, p.lO & p.ll). 2. Leaves: numerous, mostly basal, very long, narrow, curving, and tapering gradually to a fine point; leaf margin scabrid ( 1) ; ligule a fringe of soft stiff hairs (Fig. 1, p.2). 3. Flowers: in large plume-like panicles (flower heads) on stout culms up to 6 m long (Fig. 1, p.2); panicles, composed of thousands of spikelets, each consisting of several flowers protected by two outer bracts (glumes) (Fig. 1, p.2); each flower enclosed between two small bracts, the pal ea and the lemma. 4. Seeds: wind dispersal assisted by long fine hairs on the lemma (Fig. 3, p.5); during dispersal seeds remain enclosed between the lemma and palea. Seedlings of Cortaderia can usually be distinguished from other grasses and sedges found in New Zealand by the combination of a hair­ fringed ligule (Fig. 1, p.2), serrated leaf margins, and distinctive leaf sheaths that become whitish or glaucous in the native species (Plate 5, p.21). The breeding systems of cortaderia spp. have been described in detail by Connor (1963, 1965a, 1965b, 1974, 1983). The native species are gynodioecious and, although c. selloana is gynodioecious in organisation, it behaves dioeciously in nature. In the native species and in c. selloana but not in c. jubata, plants are of two sex forms. Female flowers are functionally female through male sterility and must be cross-pollinated to set seed. In the female flowers of c. selloana the sterile anthers are not longer than 0.1 mm, whereas in the native species female flowers have sterile anthers approximately half the size of the pollen-producing anthers of the hermaphrodites. Hermaphrodite flowers of the native species and c. selloana have both anthers and pistils. The native species are self-compatible and self-pollination is estimated to occur in about 75\ of flowers, but in c. selloana hermaphrodites are self-sterile and require pollen from other hermaphrodite plants if seed is to set. (1) Technical terms are defined in Appendix 3 - Glossary of Terms. 4 FIG. 2- DIAGRAMMATIC REPRESENTATION OF FLORETS AND FLOWERS IN CORTADERIA --- awn stamen lemma HERMAPHRODITE FLORET HERMAPHRODITE FLOWER (stigmas enclosed) ~awn sterile stamen FEMALE FLOWER FEMALE FLORET AS IN NATIVE SPECIES (sterile stamens minute in C.jubata and female C.selloana) 5 FIG. 3- DORSAL ASPECT OF LEMMAS FEMALE HERMAPHRODITE C.JUBATA C.SELLOANA FIG. 4- CORTADERIA FULVIDA FLORETS ~awn pale a ~~~~---lemma----~~~~ll~ ---hairs--- HERMAPHRODITE FEMALE (stigmas enclosed) 6 In c. jubata all plants are female, there is no pollination, and reproduction is by autonomous apomixis [Connor 1965a (as c. atacamensis}, connor 1974]. The haploid mother cell, which normally forms the embryo sac, dies and is replaced by a diploid cell from the surrounding wall. The seed develops precociously while still enclosed in the sheath, and by the time the flower opens the seed is well developed (Philipson 1978}. There is not the marked succession of enlarging seeds that is often seen in sexually reproducing material (Connor 1974}. THE INTRODUCED SPECIES (PAMPAS GRASSES) 1 Cortaderia selloana (pampas g rass)( ) Cortaderia selloana (Schult.} Asch. et Graeb. is native to Brazil, Argentina, and Uruguay (Connor & Edgar 1974) and also Chile (Acevedo 1959}, occurring in damp places, depressions, and near water courses (Jacques 1957}.