MONOCOTS: (III) The commelinoid monocots

Transcription

1 MONOCOTS: (III) The commelinoid monocots NOTE: FLORAL FORMULAE LISTED HERE AND IN LATER LECTURES ARE TEXT ONLY, AND THEREFOR INCOMPLETE OVERVIEW What are the commelinoid monocots? Economic importance; importance in the Albertan flora Description of 4 select families in the orders

2 What are the commelinoid monocots? Overall circumscription of APG system is very similar to Dahlgren s superorder Commelinanae: Incorporates: (1) Palms and relatives (ARECALES; 1 family) (2) Grasses, sedges and relatives (POALES; 16 families) (3) Gingers, bananas and relatives (ZINGIBERALES; 8 families) (4) Commelinacous taxa (COMMELINALES; 4 families) Plus an assortment of odds and ends of more poorly placed taxa (eg Bromeliaceae) Characteristics & synapomorphies Most of the order are herbaceous (some big exceptions, eg the Palms) Many taxa in the biggest order (Poales) are wind-pollinated The commelinoids are traditionally viewed as advanced monocots grasses and relatives recognized as highly derived in floral morphology. The wind-pollinated taxa show extensive reduction in floral and inflorescence morphology this is often difficult to interpret Three major synapomorphies for the clade: Copiously starchy endosperm Stuctured epiculticular wax UV-fluorescent cell walls

3 Economically important plants Many taxa with major economic importance POALES POACEAE major cereal crops Oryza sativa Rice Zea mays Maize Hordeum vulgare Barley Triticum aestivum Wheat Avena sativa Oats Secale cereale Rye Sorghum bicolor Sorghum Pennisetum americanum Millet Saccharum officinale Sugarcane & Bambusa Bamboo (major source of timber). Plus many ornamentals and other minor food, fodder and fibre crops ZINGIBERALES Many crops and ornamentals MUSACEAE Musa Banana, plantain ZINGIBERACEAE Zingiber Ginger Elettaria Cardamom Kaempferia & Alpinia Galanga(l) ARECALES Several crops and ornamentals Phoenix Date palm Cocos Coconut BROMELIACEAE One major crop: Ananas comosus (pineapple)

4 Commelinoid monocots in Alberta POALES Poaceae (Grasses) many species ~60 genera, incl. -- Agrostis (bent grasses) Festuca (fescues) Poa (meadow grass) Bromus (bromes) Cyperaceae (Sedges) 7 genera, incl. -- Carex (sedges) many species Cyperus ( papyrus ) Eleocharis (spike rush) Scirpus (bulrush) Juncaceae (Rushes) 2 genera Juncus (rush) Luzula (wood rush) Typhaceae (Cat-tails) 1 sp. -- Typha latifolia Sparganiaceae - (Bur-reeds) 6 spp. -- Sparganium spp.

5 Commelinaceae R. Brown (Spiderwort family) Widespread tropical to temperate 40 genus, 640 species None in AB Major genera: Commelina, Tradescantia One of several insect pollinated commelinoid families; Showy perianth parts (petals and sepals) Flowers open for a day or less, then deliquesce! Large diversity of deployment of sex organs within each flower Habit Leaves Floral Pollination Fruit dispersal Herbs (can be succulent), well dev. stems, swollen at nodes Alternate and along stem; Simple; Linear to expanded blade; Sheathing at base (closed sheath); No stipules Usu. bisexual, radial to lateral, sepals plus petals Determinate inflorescences 1 to few helicoid cymes Pollen-collecting bees/ wasps (no nectaries) Animal and winged Floral formula 3, 3, 6 (or ), 3 Loculosidal Capsule Axile placentation, 1 to several ovules per locule Seeds with conspicuous conical cap Hairy filaments, hairs often moniliform (bead-like) Mimic pollen?

6 Typhaceae A. L. de Jussieu (Cattail family) Widely distributed, esp. N. Hemisphere. Aquatic & wetland habitats, esp. marshes 1 genus, 13 species (Sparganiaceae treated separately) Highly clonal, often form large, uniform stands Low genetic variation worldwide Habit Rhizomatous, aquatic herbs, Emergent or partly floating Leaves Alternate; Simple and entire; Linear; Sheathing at base; No stipules Distychous (2-ranked) and often spongy Floral Unisexual (monoecious), radial, reduced flowers Densely clustered spike-like inflorescences. Determinate, terminal Male flowers above female Pollination Wind (no nectaries) Fruit dispersal Wind dispersal (perianth bristles assist) Floral formula Staminate: -1-infinity-, 1-8, 0 Pistillate: -3-infinity-, 0, 1 Achene-like follicle One ovule per flower (apical placentation); Usu. 1 of 3 carpels is functional Reduced tepals (bract, bristle or scale-like) numbering 6 or less Economic importance: Occasional ornamentals or weaving material. Edible pollen, young male axis, and rhizomes

7 Cyperaceae A. L. de Jussieu (Sedge family) Worldwide. Often in damp sites 122 genera, 4500 species Closely related to Juncaceae, APG has each family in Poales Often mistaken for grasses but sedges have edges and rushes are round, but grasses have nodes from their tips to the ground ). Stem usu. triangular in c-s, usu. lack ligules (cf. most grasses) Inflorescence subunits = spikelets (actually very reduced inflorescences) The spikelet prophyll (first leaf on axis) can be highly modified, eg in Carex, into a sac (perigynium) that completely encloses the flower The flower can be a reduced 1-flowered inflorescence axis Habit Leaves Floral Pollination Fruit dispersal Rhizomatous herbs, annuals and perennials Alternate, tristychous (3-ranked). Simple, ~entire leaf divided into blade and sheathing base, the sheath closed Reduced and sometimes difficult to interpret Each flower (Carex) can be a spikelet. True flowers are unisexual (all Carex) or bisexual. If unisexual, plants usu. monoecious Wind (nearly all) no nectaries Water & wind Floral formula -0-6-, 1-3, 3 Achene Tepals lacking or highly reduced 1 ovule per carpel, basal placentation Pollen produced in pseudomonads (pollen released as 4 microspores but 3 become degenerate) Economic importance: Limited: Some ornamentals; Weaving and packing materials Papryus = Cyperus papryus

8 Poaceae Barnhart (= Gramineae A. L. de Jussieu) (Grass family) Worldwide. Desert to aquatic. Grasslands (Prairies, stepes, pampas, veldt). Some woody species bamboo forests ~650 genera, 8700 species (4th. largest plant family) Most important family, economically; Dominant family on much of earth (quarter of land vegetation). Major subfamilies include Pooideae and Panicoideae. Phylogenetic relationships well worked out (Page 100, Box 5A) Inflorescence subunits = spikelets (each actually very reduced inflorescences) Habit Leaves Floral Pollination Fruit dispersal Herbs (often rhizomatous). Bamboos = trees Alternate, distychous. Leaf = sheath, ligule, blade. Sheath margins overlapping but usu. not fused. Meristems at base of internodes, blades and sheaths Continuous growth from base. Tolerant to fire and grazing Various forms of ligules. Leaf blades simple, usu. linear. Reduced flowers (bisexual or unisexual, pl. monoecious or dioecious) = flower has extremely reduced perianth (mostly 2); lodicules Floret = minute, 1-flowered inflorescence axis Each floret subtended by palea (prophyll) and lemma Each spikelet of florets subtended by two additional bracts (glumes) Inflorescence of spikelets may be spike, panicle, cyme, raceme Usu. wind-pollinated Various Floral formula -2-, (1-) 3 (-6), 2-3 Usu. caryopsis (fruit wall fused to seed) One subapical to near basal ovule per locule Embryo with a highly modified cotyledon (scutellum) Economic & social importance: Paramount importance to humanity: Most major civilizations are based on the triploid endosperm of the grasses Grasslands first appeared recently (Miocene, 5-25 MYA) 70% of farmland, 50% of our calories, domestication for over 10,000 years. Grasses also used for fermented and distilled beverages, fodder crops, fuel, timber, fiber, pulp, erosion control, and some are grown as ornamentals and lawn grasses