Grass Systematics

Generalized Key to Groups in FL.

Single spikelets

Paniceae (no consistently awn tipped lemmas, spikelets not paired, panicoid spikelets)
Andropogoneae (awn tipped lemmas, spikelets paired, panicoid spikelets-elongate)
Aristidoideae (three awns, no panicoid spikelet, special C4)
Erhartoideae (boat shaped glume, C3)
Aristidoideae (three awns)
Pharoideae (upside down wide leaves, hooded velcro spikelets C3)

Multiple spikelets

Bambusoideae (woody, C3, pseudopetioles, dimorphic lvs.)
Pooideae (not woody, no boat shaped glume, C3)
Chloridoideae (not woody, no boat shaped glume, C4)
Arundinoideae (very large grasses but not woody - flowers usually hairy)
Danthonioideae (Glumes exceed entire spikelet, C3)
 

Pooideae vs. Chloridoideae

1.   Pooideae is C3, blooms early in the year in rich soils, and has few representatives in Florida, usually has distinctly expanded nodes.

2  Chloridoideae is C4, blooms late, and has many representatives in Florida, nodes not expanded - maybe only a small bump.  Assume its this if choice is between Pooideae vs. Chloridoideae in FL.



 
 

Thumbnail Sketches

PADACC = PACC Clade

Subfamily: Panicoideae

Generally, these are C4 grasses with panicoid spikelets (with a single fertile floret in the spikelet almost always with a non-female fertile floret below it and often dorsally compressed) - 1st glume, 2nd glume, sterile lemma, lemma, palea, ovary.  Ligules of either a fringe of hairs or sometimes membranaceus.  The stems tend not to be hollow.  Inflorescences are some type of panicle (sometimes spikelike or a onesided spike) - sometimes a panicle of one sided spikelike segments.  Half of Florida grasses are from this subfamily.  The subfamily is divided into the Paniceae and Andropogoneae.

PANICEAE

ANDROPOGONEAE

Subfamily: Chloridoideae (Eragrostoideae)

Generally, these are C4 grasses with non-panicoid spikelets (sterile florets - if any, above the fertile ones) and ligules of either a fringe of hairs or sometimes membranaceus.  Inflorescences are some type of panicle (or rarely a one-sided spike) - either open or made up of one-sided, spike-like segments.  Often 2 prominent keels on palea.

CHLORIDOIDEAE

ARUNIDINOIDEAE

Arundinoideae has traditionally been a “wastebasket” group for alot of genera but in its new circumscription has some molecular characters.  It contains Phragmites, Cortedaria, and Arundo.  These are very big plant with plumes, memorize them.

Cortedaria - long thin leaves that are very rough because of antrose barbs, hard huge midrib, leaves from base of plant, clumper.  Male and female plants.

Phragmites - runner, leaves not rough and about 2 cm wide.
Note: Phragmites is often mistaken for Neyraudia (of the Chloridoideae). The nodding inflorescence, much larger spikelets and non-persistent leaf sheathes of Phragmites differentiate it.

Arundo - leaves 4 cm wide, much bigger inflorescence than Phragmites, huge plant.
 

CENTOTHECOIDEAE

Centothecoideae contains only Chasmanthium in FL (found mostly in mesic woods).
 
 

BEP = BOP Clade

BAMBUSOIDEAE

Running Rhizomes

Arundinaria (erect branches 1-3 at a node following the stem, round culm)
Phyllostachys (Usually paired branches, distinct sulcus)

Clumping Rhizomes

Bambusa

ERHARTOIDEAE (Oryzoideae)

Characterized by a flattened lop-sided spikelet that is always inflated and with no glumes.   draw picture   Membranous ligule and often 6 stamens.  The major genera in the SE are:
Oryza - found in south Fl., what appear to be glumes are actually reduced florets.
Leersia - looks like Oryza but without the “glumes”.
Luziola (Hydrochloa) -  hard lemmas.
Zizania - long awns, huge ligules.
Zizaniopsis - bigger ligules than Zizania and leaves broader and more basal, short or no awns.
 

POOIDEAE