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• Dichotomous Key
• Poaceae
• Poaceae Group 10
• Piptochaetium
• Piptochaetium avenaceum

Piptochaetium avenaceum — black-seeded spear grass

Facts

Black-seeded spear grass may be one of the most easily recognized grasses, with its long, straight, slender, and on close inspection, twisted awns, and black caryopsis (fruit). It inhabits sandy or rocky woodlands in Connecticut, Massachusetts and Rhode Island.

Habitat

Cliffs, balds, or ledges, ridges or ledges, woodlands

Characteristics

• Flowers

  Anther length

  0.3–4 mm

  Anther number

  3

  Awn on glume

  the glume has no awn

  Bristles below spikelets

  no

  Floret lower bract texture

  the lemma is hard and firm

  Floret number

  1

  Floret types within spikelet

  all the florets within a spikelet are similar

  Glume awn length

  0 mm

  Glume relative length

  one or both glumes are as long or longer than all of the florets

  Glume shape

  the glume is flat or curved in cross-section

  Glume veins

  • 3
  • 5

  Glumes per spikelet

  2

  Inflorescence arrangement

  the spikelets are uniform

  Inflorescence axis orientation

  • the inflorescence axis is arched or curved outward
  • the inflorescence axis is straight

  Inflorescence branch length

  2–4 cm

  Inflorescence branch roughness

  the inflorescence branches are somewhat to very rough

  Inflorescence branches

  the flowers are attached to branches rather than to the main axis of the inflorescence

  Inflorescence branches coming off the lowest stem node

  2

  Inflorescence crowding

  the panicle is somewhat to very spread out, with clearly-evident branches

  Inflorescence length

  140–220 mm

  Inflorescence length to width ratio

  3.7–4.7

  Inflorescence type (general)

  the spikelets are borne on stalks or on branches

  Inflorescence type (specific)

  the inflorescence is branched, and the branches do NOT both grow from the same side of the plant AND look like spikes

  Inflorescence width

  30–60 mm

  Inforescence position

  the spikelets are mainly carried at the end of the stem

  Lemma awn base

  the awn is attached right at the tip of the lemma

  Lemma awn coiled

  the lemma awn is coiled at least one half turn

  Lemma awn length

  45–70 mm

  Lemma awn number

  the lemma has one awn on it

  Lemma awn orientation

  • the awn of the lemma is straight
  • the awn of the lemma on dried or older plants is curved or bent outwards

  Lemma base hairs

  the lemma has hairs at the base

  Lemma base length

  2–3 mm

  Lemma cross-section

  the lemma is flat or rounded if you cut across the midpoint

  Lemma hairs

  the lemma has fine hairs between the veins

  Lemma keel hairs

  NA

  Lemma surface

  the surface of the lemma is relatively smooth (not counting any longitudinal veins or hairs)

  Lemma tip

  the lemma tip is a simple point, with or without an awn (long narrow extension ending in a point)

  Lemma vein number

  5

  Lower glume length

  9–15 mm

  Lower glume relative length

  the lower glume is nearly as long, or as long as, the upper glume

  One or more florets

  there is one floret per spikelet

  Palea length

  7–14 mm

  Palea relative length

  palea is longer than lemma

  Reproductive system

  all the flowers on the plant have both carpels and stamens (synoecious)

  Spikelet axis tip

  there is no extension of the spikelet axis beyond the tip of the spikelet

  Spikelet disintegration

  the spikelet breaks off above the glumes, so that after the florets fall off, the glumes remain

  Spikelet length

  9–15 mm

  Spikelet number per node

  Up to 0

  Spikelet pedicel

  the spikelets have pedicels

  Spikelet pedicel length

  15–50 mm

  Spikelet position

  the spikelets emerge mainly from the upper halves of the inflorescence branches

  Spikelet shape

  • the spikelets are lanceolate (lance-shaped, widest below the middle and tapering narrowly to the ends) in profile
  • the spikelets are oblanceolate (lance-shaped, but with the widest point above the middle) in profile

  Spikelet width

  At least 1 mm

  Spikelets per panicle branch

  1–2

  Spikelets spiny

  the spikelets do not appear spiny

  Tip of glume

  the tip of the glume is not divided (though it may have an awn on it)

  Upper glume length

  9–15 mm

  Upper glume relative length

  the upper glume is more than one half as long as the lowest lemma

  Upper glume shape

  the upper glume is widest at or below the middle

• Fruits or seeds

  Groove on seed

  the caryopsis does not have a groove on it

  Seed length

  3.5–6 mm

• Growth form

  Lifespan

  the plant lives more than two years

  Rhizomes

  no

  Roots

  there are only slender roots on the plant

• Leaves

  Leaf auricles

  the leaves do not have auricles

  Leaf basal lobe hairy

  NA

  Leaf blade cross-section

  • the leaf blade is clearly folded or rolled inwards
  • the leaf blade is more or less flat in cross-section, or slightly folded or rolled inwards

  Leaf blade hairs

  the leaf blade is hairless, but it may have tiny prickles that give it a sand-papery feel

  Leaf blade length

  8–30 cm

  Leaf blade texture

  • the leaf blade is rough and sandpapery
  • the leaf blade is smooth, or it may have soft hairs

  Leaf blade width

  0.5–3 mm

  Leaf ligule length

  0.4–3.3 mm

  Leaf ligule type

  the leaf ligule is in the form of a membrane

  Leaf margin glands

  there are no glands along the edges of the leaf blade

  Leaf sheath closed around stem

  the margins of the leaf sheath are overlapping and not fused together except in the basal half (or less)

  Leaf sheath hair type

  there are no hairs on the surface of the leaf sheath

  Leaf sheath hairs

  there are no hairs on the surface of the leaf sheath

  Orientation of topmost leaf

  the flag leaf is held upright, or at less than a 45 degree angle out from the stem

• Place

  Habitat

  terrestrial

  New England state

  • Connecticut
  • Massachusetts
  • Rhode Island

  Specific habitat

  • cliffs, balds, or ledges
  • ridges or ledges
  • woodlands

• Stem, shoot, branch

  Hairs at nodes

  the stem nodes are hairless or they have very sparse hairs

  Plant height

  30–100 cm

  Stem hairs

  the stem is nearly to completely hairless

  Stem node number

  2–3

  Stem orientation

  the stems are upright

  Stem spacing

  the stems grow close together in compact clusters or tufts

Wetland status

Usually occurs in non-wetlands, but occasionally in wetlands. (Wetland indicator code: FACU)

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae