Seed Structure Grass Seed Collection of cleaned, mature florets Matured Florets Bluegrass Fescue Ryegrass Bentgrass Flowering Floret Grass Flower Three stamens Each with one anther and one stigma One ovary One ovary Two feathery stigmas Two lodicules at the base Two bracts Palea and lemma 1
Matured Floret Two bracts enclose the fruit Caryopsis developed from the ovary Caryopsis Dry fruit Ovary wall (pericarp) fused to seedcoat Caryposes Spikelet Florets attached by its base (callus) to the rachilla Two bracts (glumes) at lower end of the spikelet Fescue Bluegrass Bentgrass Spikelet Bentgrass: one floret and two glumes Ryegrass: up to 20 florets and one glume Spikelet borne in inflorescence Inflorescence Open Panicle Compressed Panicle Spike 2
Inflorescence Floret Identification Transition from vegetative to floral growth and development Stem elongation Inflorescence Floret Directions Front view Palea is facing toward you. Rachilla is seen arising from the callus base. Side view Side of the lemma is seen as it curves about the palea. Back view Lemma faces toward you Rachillae Stem-like segment Protrudes up from the callus on the palea side Missing in bentgrass floret Bluegrass Fescue Ryegrass Bentgrass Nerves on Lemma Lateral nerves along the edges of the lemma Mid-nerve running down the middle of the lemma from apex to base. Awn Arise from the mid-nerve halfway from apex to base. Absent in the bluegrass. Fescue Ryegrass Bluegrass Bentgrass 3
Pubescence (hairs) on the floret Types Wispy masses to individually spaced stiff hairs. Location At the base, on the lemma, or along any of the nerves. Maybe lost during cleaning Seed Identification Largest florets 6mm average length Sample Size: 10 florets Magnification: Hand lens Ryegrass rachilla Wide and flattened against the palea. Oblong top Fescue rachilla Narrow cylindrical Circular upper end and somewhat flared 4
Floret Shape Ryegrass rectangular appearance Fescue somewhat elliptical Inflorescence Ryegrass spikes Fescue panicels Spikelets Ryegrass 6-20 florets Tall fescues 6-8 florets Fine fesuce 4-7 florets Long, slender awn on annual ryegrass Ryegrasses Fescues Tall fescue Wide and flattened front to back Awn may be present Fine Fescue Narrow and cylindrical Floret arches away from the palea side awn appears as a narrowed extension of the whole lemma Medium size floret 2.5 mm average length Sample size: 25 florets Magnification: hand lens or dissecting scope 5
Inflorescence Open to compressed panicles 2 to 3 florets per spikelet in rough bluegrass 3 to 6 florets in other species Poa annua Poa compressa Poa pratensis Poa trivialis Canada bluegrass Smooth lemma No visible intermediate nerves Widening of the lemma above the middle Rough bluegrass Remnant of basal pubescence Prominent intermediate nerves Lemma straight along its edges Edges of the lemma folded over the palea. Kentucky bluegrass Pubescence completely removed Lemma edges tend to curve Lemma edges wrapped more weakly about the palea Annual bluegrass Very prominent intermediate,lateral and midnerves Pubescence may be seen along any or all of these nerves in abundance Palea and lemma appear to be sucked in tightly 6
Very small florets 1.5mm average in length Can be difficult to identify Sample Size: 50 florets Inflorescence open or compressed Agrostis alba Agrostis Cania Agrostis Agrostis palustris tenuis Spikelet One floret and two glumes Typical bentgrass sample May contain several spiklelets Size, color, retained pedicels 7
Velvet bentgrass Most awns entact Bent awn, arsing from mid-rib about one half of the way from base to apex Five nerves below awn s point of attachment, four above. Palea is rudimentary Lemma grainy Colonial bentgrass Shiny paleas and lemmas 3 or 5 nerves visible Variable length of palea Stiff hairs arising from the lemma surface Awn originating from near the callu Creeping bentgrass Awn rarely present Remaining stub on the mid-nerve toward the apex. 5-nerved lemma is more often Palea longer than the caryopsis Stubby basal hairs Shinny bract Redtop, Difficult to distinguish from creeping BG More often 3-nerved Usually longer basal hair Palea as long as the caryopsis Seed Identification Many varieties deviate in floret phenotype (outward physical characteristics) from the norm for that species Seed Quality Purity Percentage of pure seed of an identified species or cultivar Remaining percentage inert matter, weed seeds, and other crop seeds Viability Percentage of seed that is alive and will germinate under standard conditions 8
Seed Quality Seed Quality Pure Live seed (PLS) Product of purity and viability 92% Purity x 80 %Viability = 73.6 % PLS. Compare seed prices Actual cost of pure live seed = Cost per pound of seed x 100 PLS % 9