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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Zoysia Willd.

After Karl von Zois, 1756–1800, country gentleman and plant-collector of Carniola, Austria.

Type species: Type: Z. matrella (L.) Merrill.

Including Brousemichea Bal., Matrella Pers., Osterdamia Necker ex Kuntze

Habit, vegetative morphology. Mat forming perennial; rhizomatous. Culms 5–50 cm high; herbaceous; sparsely to amply branched above, or unbranched above. The branching simple. Culm nodes glabrous. Culm internodes solid. Leaves not basally aggregated; conspicuously distichous; non-auriculate. Leaf blades very narrow; flat, or rolled; without abaxial multicellular glands; not pseudopetiolate; without cross venation; persistent; rolled in bud. Ligule a fringed membrane to a fringe of hairs.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence reduced to a single spikelet (in Z. minima), or few spikeleted to many spikeleted; a false spike, with spikelets on contracted axes, or a single raceme; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; shortly pedicellate.

Female-fertile spikelets. Spikelets 2.3–3.4 mm long; adaxial; compressed laterally, or not noticeably compressed, or compressed dorsiventrally; falling with the glumes (falling singly from the persistent pedicels). Rachilla terminated by a female-fertile floret. Hairy callus absent. Callus absent.

Glumes present; one per spikelet, or two; very unequal; exceeding the spikelets; (the upper) long relative to the adjacent lemmas; awned (or mucronate, via the excurrent midnerve), or awnless; very dissimilar (the lower when present minute and scarious). Lower glume 0 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.

Female-fertile florets 1. Lemmas less firm than the glumes (hyaline); not becoming indurated; entire; blunt; mucronate; hairless; non-carinate; 1 nerved. Palea present, or absent; when present, conspicuous but relatively short, or very reduced; not indurated; 1-nerved, or nerveless. Lodicules absent. Stamens 2, or 3. Anthers 1.3–3 mm long; not penicillate. Ovary apically glabrous. Styles fused, or free to their bases. Stigmas 2; white.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small; compressed laterally. Hilum short. Pericarp fused. Embryo large; not waisted. Endosperm hard; without lipid; containing compound starch grains. Embryo with an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins meeting.

Seedling with a long mesocotyl. First seedling leaf with a well-developed lamina. The lamina broad; erect.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent (but abundant adaxially). Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; more or less spherical; clearly two-celled; chloridoid-type. Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs with ‘partitioning membranes’ (in Z. macrantha). The ‘partitioning membranes’ in the basal cell. Microhairs (27–)28.5–30(–31.5) microns long. Microhair basal cells 15 microns long. Microhairs (13.5–)15.5–16.5 microns wide at the septum. Microhair total length/width at septum 1.5–2.2. Microhair apical cells 10.5–12 microns long. Microhair apical cell/total length ratio 0.37–0.47. Stomata common; (18–)19.5–21(–22.5) microns long. Subsidiaries dome-shaped, or dome-shaped and triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs and not paired (some solitary); silicified. Intercostal silica bodies present and perfectly developed; crescentic. Costal zones with short-cells. Costal short-cells predominantly paired, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies present throughout the costal zones; rounded, saddle shaped, and crescentic; not sharp-pointed.

Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.

C4; biochemical type PCK (Z. japonica); XyMS+. PCR sheath outlines uneven. PCR sheaths of the primary vascular bundles interrupted; interrupted abaxially only to interrupted both abaxially and adaxially. PCR sheath extensions present. Maximum number of extension cells 4–6. PCR cell chloroplasts with well developed grana; centrifugal/peripheral. Mesophyll with radiate chlorenchyma; traversed by columns of colourless mesophyll cells. Leaf blade adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans (these often linked with the abaxial epidermis by columns of colourless cells). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.

Cytology. Chromosome base number, x = 10. 2n = 40. 4 ploid. Chromosomes ‘small’.

Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Zoysieae; Zoysiinae. 10 species.

Distribution, phytogeography, ecology. Mascarene Is. to New Zealand.

Commonly adventive. Xerophytic; species of open habitats; halophytic. Coastal sands and hinterland.

Economic aspects. Significant weed species: Z. matrella. Cultivated fodder: Z. macrantha (in coastal sand and brackish places). Lawns and/or playing fields: Z. japonica, Z. matrella, Z. tenuifolia.

Rusts and smuts. Rusts — Puccinia.

References, etc. Leaf anatomical: Metcalfe 1960; studied by us - Z. macrantha Desvaux.

Illustrations. • Z. matrella, as Osterdamia: Lamson-Scribner (1900), American Grasses III. • Z. macrantha, habit and habitat. Zoysia macrantha. Sand dunes, Narooma, New South Wales. • Z. macrantha, abaxial epidermis of leaf blade: this project. • Z. macrantha, TS leaf blade: this project. Zoysia macrantha. Bulliforms and colourless cells forming columns traversing the mesophyll; PCR sheaths with extension cells. • Z. macrantha, TS leaf blade: this project

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., Macfarlane, T.D., and Dallwitz, M.J. 1992 onwards. The grass genera of the world: descriptions, illustrations, identification, and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens, world and local distribution, and references. Version: 11th December 2017.’.