| # The grass genera of the world |

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

### Chimaerochloa H.P. Linder

~ Cortaderia

Type species: C. archboldii (Hitchc.) Pirie & H.P Linder.

Habit, vegetative morphology. Tough, perennial; caespitose. Culms 25–140 cm high. Culm leaves present. Pluricaespitose. Plants without multicellular glands. Leaf blades not pseudopetiolate; disarticulating from the sheaths; sclerophyllus, tough. Ligule present; a fringed membrane, or a fringe of hairs (?).

Reproductive organization. Plants bisexual, all with bisexual spikelets, or dioecious (gynodioecios?); with hermaphrodite florets, or without hermaphrodite florets. The spikelets all alike in sexuality; hermaphrodite, or female-only (?). Plants chasmogamous.

Inflorescence. Inflorescence paniculate; open; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelets not secund; pedicellate.

Female-fertile spikelets. Spikelets 7–20 mm long (? - assuming the Linder et al. range includes the awns); compressed laterally; disarticulating above the glumes; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret (the Linder et al. description of the spikelets not corresponding with their illustration in this respect); the rachilla extension with incomplete florets. Hairy callus present (villous). Callus rounded or truncate, shorter to much longer thsn the rachilla internode; blunt (rounded or truncate).

Glumes two; more or less equal; shorter than the spikelets; long relative to the adjacent lemmas; hairless; pointed; awnless; similar. Lower glume much exceeding the lowest lemma; relatively smooth; 1–3 nerved. Upper glume 1–3 nerved. Spikelets with incomplete florets (cf. the Linder et al. illustration, not their desscription). The incomplete florets distal to the female-fertile florets. The distal incomplete florets presumably merely underdeveloped; awned.

Female-fertile florets 2–5 (?). Lemmas not becoming indurated; incised; apically 2 lobed (the lobes extended into long setae); not deeply cleft; awned. Awns 1; median; from a sinus; non-geniculate; straight, or flexuous; hairless; much longer than the body of the lemma. Awn bases somewhat twisted. Lemmas hairy (dorsally pilose). The hairs not in tufts. Lemmas non-carinate; 3 nerved; with the nerves non-confluent. Palea present; conspicuous but relatively short; apically notched; awnless, without apical setae; 2-nerved; 2-keeled. Palea back glabrous. Lodicules present; 2; rhomboid; with microhairs and bristles. Stamens 3, or 0. Ovary apically glabrous.

Fruit, embryo and seedling. Hilum short to long-linear (about a third of the caryopsis length). Pericarp fused. Embryo large (about half the caryopsis length).

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present (?); panicoid-type. Subsidiaries dome-shaped. Guard-cells overlapped by the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs and not paired (solitary); when paired silicified. Intercostal silica bodies tall-and-narrow.

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

C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs (the massive ribs separated by deep furrows); with the ribs more or less constant in size (broad, flat-topped). Midrib not readily distinguishable; with one bundle only. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’ (T’s and inverted anchors). Sclerenchyma not all bundle-associated. The ‘extra’ sclerenchyma in abaxial groups to in a continuous abaxial layer.

Culm anatomy. Culm internode bundles in three or more rings.

Cytology. 2n = 72.

Classification. Watson & Dallwitz (1994): genus not recognised. Soreng et al. (2015): Danthonioideae; Danthonieae. 1 species (C. archboldii).

Distribution, phytogeography, ecology. New Guinea.

Species of open habitats (in alpine grassland).

References, etc. Morphological/taxonomic: Linder et al. (2010), involving too much extrapolation/guesswork. Leaf anatomical: temporarily extracted from L.W.’s description of Cortaderia sensu lato.

Special comments. Sexuality of the plants is described and qualified using the same ambiguous wording in all the descriptions seen; viz., "gynodioecious ("male", in this context, indicating the bisexual state".). The Linder et al. (2010) table of data as encoded for phylogenetic analysis records this genus as 'gynodioecious', but their generic decription suggests otherwise ..... Fruit data wanting. Anatomical data wanting.

Illustrations. • Chimaerochloa archboldii: Linder et al, Ann. Miss. Bot. Gard. 97 (2010).

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: 15th June 2025. delta-intkey.com’.

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