2015 Hoyt Arboretum and Herbarium, HAHIntro to Grass Identification/Morphology

Exotic Grasses in Spiranthes Research Site

Erin Riggs HAH Curator, Systematic Botanist

Goals for this class:• Increase botanic visual literacy focusing

on grass morphology• Expand knowledge of native grasses and

their potential for restoration use• Expand knowledge of exotic grasses, they

are here to stay

List of resources:

Oregon Flora Project online www.oregonflora.org , Poaceae treatment is posted (artificial key) Flora of North America, Poaceae, Vol. 24, 25 (FNA are natural keys) Flora of North America, Juncaceae, Vol 22Flora of North America, Cyperaceae, Vol 23Field Guide to the Sedges of the Pacific Northwest (artificial key) Flora of North America Manual of Grasses online www.herbariua.usu.edu/webmanual Manual of Grasses for North America, field manual of grasses, complimentary to FNA online CAVEAT! Out of date publications, handy for field use, images still nice, names and taxonomy out of date. Manual of Grasse of the United States, 1971, Hitchcock (44 years old)Flora of the Pacific Northwest, 1969, Hitchcock and Cronquist (46 years old)

Definitions:

Artificial key: sequential groupings of the key by intention do not reflect natural groups; aims to most easily identify a given taxon, usually regionally focused. Does not include entire global groups- usually easier key to use.

Natural key: diagnostic features are used to delimit “natural” groups/formal taxa, include all characters for entire global groups – usually more difficult key to use

Ployclave key: consists of a list of numerous character states, the user selects all of the states that match the specimen. This is becoming more common with online keys.

GRASS MORPHOLOGY AND ID

Grass flower morphology

Inflorescence- the flowering part of a plant; a flower cluster; the arrangement of the flowers on the flowering axis. Composed of many spikelets.

Panicle

Spike Drooping panicle

Rachis- the main axis of a structure, as in a compound leaf

Spikelet - a flower cluster in grasses and sedges consisting of 1- many flowers subtended by two glumes. Glumes delimit the spikelet.

Pedicel- the stalk of a single flower or of a grass spikelet

Rachilla- the axis of a grass or sedge spikelet, with nodes and internodes

Glume- one of a pair of empty bracts at the base of a spikelet. Empty because they do not have buds or flowers in them.

Bract- a reduced leaf or leaf like structure at the base of a flower, inflorescence or spikelet.

Awn- narrow bristlelike appendage

Many flowered spikeletOne flowered spikelet; this one unable to distinguish upper or lower glume

Upper glumeLower glume

Lemma- the lower bract which subtends a grass flowerPalea-the upper bract of two that subtend a grass flower

Pistil = female parts, made up of:Stigma- part of pistil that is receptive to pollenStyle – connects stigma to ovaryOvary- contains ovules/seeds

Stamen = male parts, made up of:Anther-pollen bearing portion of stamenFilament- the stalk of the stamen

The Grass floret/flower

Lower glume

Upper glume

Lower glumeUpper glume

lemma

palea

Floret/flower parts

Upper glumeLower glume

Disarticulation - separating at maturity at a joint. An important ID character among all grasses

Disarticulation above the glumes below the floret

Disarticulation below the glumes

floret

Petals and sepals absent Petals and sepals look the same = tepals

Grasses haveHighly modified petals and sepals-We wont look at them, not used in ID

Grass Culm/stem morphology

Sedges have edges Rushes are round Grass has joints

Culm = stem

Node =joint

Grass Culm/stem- morphology

Node – position on stem where leaves or branches originate

Sheath – the base of the leaf that surrounds the stem*

Blade – broad part of leaf

Ligule- the membranous appendage arising form the Inner surface of the leaf at the junction of leaf sheath

Auricle – a small “ear shaped” appendage, usually very small

Collar – the junction ofblade and sheath

Internode – portion of stembetween nodes

Budshoot-flowers grow out thisportion

*Most of our grasses will all have hollow culms, occasionally we haveCulms that are solid.

Three ligule types, out of many forms

Auricle Not all grasses have auricles

All Bromus have a closed collar/closed leaf sheath, at times it can split open so look carefully.Our Bromus vulgaris will be more hairy.

Brachypodium sylvaticum Leaf sheath open but overlappingall the way to the node/joint.B. sylvaticum is much more hairy

Arundo donax

Node/joint

Leaf sheath is a good diagnostic character

Root and specialized stems

Perennial or annual form is Important in grass ID

Perennial - a plant living 3 or more years

Annual – a plant that germinates from seed, flowers, sets seed, and dies in same year

How can you tell? Sometimes you cant

Rhizome - perennial, a specialized horizontal underground stem, with nodes and internodes, sending out root and shoots at nodes (bamboo, ginger)

Caespitose both annual and perennial – • look for multiple old leaves • Size of clump can be a clue

Sometime you just cant tell

Perennial annual

Stolon- a specialized horizontal stem creeping along the surface of the ground, sending out roots and shoots at nodes (strawberries)

Annual rootsHow do you know its annual? Some times it is difficult to tell

If you cant tell if its annual or perennialyou have to key two directions.

Common annual fibrous root

Exotic grasses found on Hoyt Arboretum Citizen Science Spiranthes research site.

HAH=herbarium specimen on hand to studySome fresh specimens as well

Agrostis capillaris - bent grass

Agrostis genus characters you must have 40x + dissecting scope to ID to species.Difficult to ID• All spikelets alike • Inflorescence a narrow panicle, aging to spread out• Lemmas 1.2-2.5mm• Root stolons absent• Palea 0.5mm • Ligule 1.7- 8mm very wide range• Open sheath• Inflorescence feels slippery and smooth

• Ligule 1.7- 8mm very wide range

Agrostis capillaris - bent grass

• Inflorescence a narrow panicle, aging to spread out• Inflorescence feels slippery and smooth

Aira caryophyllea – hair grass Characters:• Small annual tufts • 1-55 cm tall, very elastic height• Lemmas awned • Sheaths open• Inflorescence contracted or open

Anthoxanthum odoratum – sweet vernal grassCharacters:• 25-60 cm tall• Auricles pilose-ciliate (long soft hairs)• Ligule 2-7 mm membranous, lopsided

Anthoxanthum odoratum – sweet vernal grass

• Auricles pilose-ciliate (long soft hairs)

Arrhenatherum elatius - tall oat grassCharacters:• 150cm tall (4+feet)• sheaths open and smooth• Sturdy joints, smooth• Ligule 1-3 mm

Bromus carinatus - HAH,

look-a-like! Native Bromus sitchensis

Characters:• All Bromus have a closed collar/closed leaf sheath.

Bromus sitchensis - HAHCharacters:• All Bromus have a closed collar/closed leaf sheath.

Bromus sitchensis – Alaskan brome

Ligule – 1-3 mmGlumes – glabrousLemma- glabrousLeaves – 2-9 mm wide

compared toBromus carinatus var marginates –Mountain brome

Ligule – 3-4 mmGlumes – pubescentLemma- pubescent Leaves – 1-12 mm wide

I have to compare with flora key for positive ID 98% of the time

Bromus tectorum (cheat grass) -HAH

ALL true bromes have closed collars,All Bromes are VERY difficult to ID, make collections for Erin to ID.

Characters:• Closed collar• Drooping inflorescence • Sheath softly pubescent• Awns 10-18 mm, big!

Cynosurus echinatus (dog tail grass) Characters:• early in the spring look close at the collar and ligule.• Ligule NO pilose hairs (long soft hairs)• The inflorescence one sided.

Dactylis glomerata – orchard grassCharacters:• early inflorescence congested and narrow, opens as it ages.• Ligule membranous 3-11 mm• Culm keeled, flattened

Blade cross section

Festuca rubra– fescueCharacters:• Ligules higher on the sides than in the back• Perennial caespitose• Leaves conduplicate, involute –folded they look thin and wiry

Holcus lanatus - velvet grass Characters:• Culm 2-100 cm tall• whole plant is velvety• Inflorescence contracted to open with age

Juncus species –Likely native, I will ID this summer.Characters:• Round culm NO nodes • Base of stem dark brown clasping stem leaves

Lolium perenne -perennial rye grassCharacters:• 2-10 florets per spike • One glume

Lolium multiflorum-annual rye grassCharacters:• 10-22 florets per spike• One glume

Poa – Kentucky blue grass, lawn grass,Poa are notoriously difficult to key bring to Erin to IDCharacters:• Leaf tips prow shaped• Inflorescence panicle, contacted to open• Sheaths mostly open• Long cobwebby hairs at base of floret

Schedonorus arundinaceus -tall fescueCharacters:• 1.5-2 m (6ft) tall• Look VERY close at collar auricles, they are ciliate• Wide coarse leaves.