Most monocots are herbaceous annuals or perennials that shoot each season from an underground storage organ (bulb, corm or rhizome) although some do form small woody trees (e.g. Xanthorrhoea). Many species have short stems and most leaves are basal, sometimes forming dense tussocks. The leaves are usually long and slender and have parallel venation. The floral parts are usually in 3's. When the perianth is petaloid (showy) there are usually two whorls, each of 3 parts. In the grasses, sedges and rushes, the perianth may be much reduced or absent. Below is a key that might be useful for determining the family of a flowering specimen.

A Basic Key to the Common Monocotyledonous Families of Tamania (based on floral characters).
 

1) Petaloid perianth present     a) Perianth actinomorphic (radially symmetrical)              b) Perianth zygomorphic (bilaterally symmetrical)	LILIACEAE  XANTHORRHOEACEAE  AMARYLLIDACEAE  IRIDACEAE  ORCHIDACEAE
2) Petaloid perianth absent     a) Flowers arranged in spikelets        (i) Leaves conspicuous              (ii) Leaves reduced to sheathing scales  b) Flowers arranged in clusters	CENTROLEPIDACEAE  POACEAE (GRAMINEAE)  CYPERACEAE  RESTIONACEAE  JUNCACEAE

 

LILIACEAE - lily family

Plants herbaceous. Leaves often linear and grass-like arising from a bulb, tuber, corm or rhizome. Flowers actinomorphic, usually bisexual. Inflorescence often a raceme. Perianth 2 whorls of 3 tepals, free or united; stamens 6; carpels 3; ovary superior. Fruit usually a capsule or berry.

Best known genera include: Astelia, Blandfordia, Burchardia, Dianella, Drymophila, Milligania.

XANTHORRHOEACEAE- grass-trees, mat-rushes

Small trees or perennials with more or less woody stems. Leaves are tough and linear. Flowers radially symmetrical, usually bisexual but sometimes unisexual in Lomandra. Inflorescence may be spike-like or flowers may be solitary. Tepals 6, in 2 whorls of 3, free or united; stamens 6; carpels 3, united; ovary superior. Fruit usually a capsule.

Best known genera include: Lomandra, Xanthorrhoea

AMARYLLIDACEAE- amaryllis family

Plants herbaceous. Leaves linear arising from a bulb. Flowers actinomorphic, bisexual. Inflorescence usually an umbel, borne on a scape (stalk). Perianth 2 whorls of 3 tepals, free or united; stamens 6; carpels 3; ovary often inferior. Fruit a capsule or berry.

Mostly naturalised aliens, e.g. Agapanthus, Allium, Narcissus.

IRIDACEAE - iris family

Plants herbaceous. Leaves often linear and grass-like forming a rosette or a tuft and arising from a bulb, corm or rhizome. Flowers bisexual. Inflorescences various, often panicles. Perianth of 6 tepals, inner or outer whorlk may be united to form a tube; stamens 3; carpels 3; ovary inferior. Fruit a capsule.

Best known genera include: Campynema, Diplarrena, Hewardia, Patersonia.

ORCHIDACEAE - orchid family

Most orchids are perennial herbs, arising annually from rhizomes, tubers or thickened rootstocks. Flowers zygomorphic with one petal (the labellum) very different from the others and a central column; stamen 1, fused with the style; ovary inferior.

Best known genera include: Caladenia, Cryptostylis, Diuris, Prasophyllum, Pterostylis, Thelymitra.

CENTROLEPIDACEAE

Leaves radical; small moss-like plants < 10 cm. Flowers unisexual or bisexual subtended by 2 or more longer, subequal bracts; one stamen; fruit dehiscent.

Best known genera include: Centrolepis, Gaimardia.

POACEAE (GRAMINEAE) - grasses

Plants herbaceaous. Culms (upper stalks) usually terete (circular in cross-section), with hollow internodes. Leaves sheathing, open, ligules present (small flap of tissue at the junction of the leaf blade and sheath). Flower bisexual subtended by two bracts (palea + lemma); perianth segments 2, in 1 whorl. Fruit circular in cross section; pericarp and testa fused.

Best known genera include: Agropyron, Agrostis, Deyeuxia, Danthonia, Eragrostis, Hierochloe, Poa, Setaria, Sporobolus, Stipa, Tetrarrhena.

CYPERACEAE - sedges

Leaves sheathing, closed, ligules absent. Stems solid, often triangular in cross-section. Flowers bisexual subtended by 1 bract. Perianth segments 0-6, in 1 whorl. Fruit often triangular in cross-section, pericarp and testa free from one another.

Best known genera include: Carex, Carpha, Cladium, Gahnia, Gymnoschoenus, Lepidosperma, Oreobolus, Schoenus, Scirpus, Unscinia.

Table 2. Differences between Cyperaceae and Graminae
 

CYPERACEAE	GRAMINEAE
Stems usually solid and triangular in cross-section; ligules usually absent.	Internodes usually hollow and stems usually circular in cross-section; ligules usually present.
Leaf sheath closed.	Leaf sheath not closed.
Inflorescence usually subtended by one or more leaf-like involucral bracts.	Inflorescence not usually subtended by leaf-like involucral bracts.
Spikelets not usually subtended by bracts, individual florets usually subtended by one bract.	Spikelets usually subtended by two bracts, individual florets also usually subtended by two bracts.
Perianth absent or represented by up to 6 scales or bristles.	Perianth usually represented by 2 lodicules.
Pericarp and testa usually free from one another, embryo surrounded by the endosperm.	Pericarp and testa usually fused, embryo usually on one side of the endosperm.

 

RESTIONACEAE

Perennial herbs. Flower unisexual, subtended by 1 bract. Perianth segments 4-6, in 2 whorls; loculi of the ovary 1-3, ovules 1 per loculus.

Best known genera include: Calorophus, Hypolaena, Lepidobolus, Leptocarpus, Restio.

JUNCACEAE

Leaves often reduced to basal sheathing scales. Flowers bisexual. Perianth segments 6 free and equal scarious parts, in 2 whorls; carpels 1-3, ovules commonly 1 per loculus; fruit a nut.