BOTANY OF THE MAYA AREA


 The grass flora is somewhat larger, and more varied than that of the
 northern part of the Yucatan Peninsula. For the most part the species
 are those which are rather wide-spread through tropical and subtropical
 America. Mesosetum filifolium Hubb. and Axonopus ciliatifolius are appar-
 ently endemic in British Honduras. Ichnanthus lanceolatus is known only
 from the Yucatan Peninsula. A few others are confined to our region and
 the adjacent countries.
 The economic grasses are those usually grown in the tropics, including
 maize (Zea mays L.), sugarcane (Saccharum officinarum L.), sorghum
 (Sorghum vulgare Pers.), Guinea grass (Panicum maximum Jacq.), and
 Para grass (Panicum purpurascens Raddi). Lemon grass (Cymbopogon
 citratus (DC.) Stapf) is commonly planted.
 Common names are included for the economic species and for any others
 that have acquired a significant local or native name. Carrizo is a term
 usually applied to any coarse woody grass, such as Olyra latifolia and
 species of Lasiacis.
 Fifty-eight genera and one hundred and sixty-one species are included.
 Through the courtesy of the directors, the specimens in the Gray Her-
 barium, and the herbaria of the New York Botanical Garden, the Field
 Museum, and the University of Michigan have been examined in the prepa-
 ration of the manuscript.

 KEY TO GENERA

SCulms hard, woody.
-Culms tall, erect, usually in large clumps.
 Plants spineless; palea wingless on the keels..... .. ... ...-. L.ambnsa
 Plants spiny at the nodes; palea winged on the keels.---.... 2. Guadua
 -Culms widely spreading or clambering, not in large clumps.
 Flowering branches numerous, in dense fascicles; spikelcts
 racemorse, subcylindrical, with 3 fertile florets .......... 3. Arthrostylidium
 Flowering branches not in dense fascicles; spikelets panicu-
 late, subspherical, with 1 fertile floret.... _..........-.. 35. Lasiacis (Panicem)
'Culms herbaceous.
-Spikelets in groups of 3 or 4, the groups racemose on a. common
 axis, the first glumes indurate, forming a pitcher-shaped in-
 volucre ............. -.......- - -.. .....-.----- 10. Anthephora
 -Spikelets not in groups with a pitcher-shaped involucre.
 'ISpikelets with 2 or more perfect florets, if only one-flowered
 the spikelets sessile on one side of a continuous rachis.
 (See also Zea and Tripsacum with unisexual spikelets.)
 \Spikelets sessile or short pedicellate on one side of a con-
 tinuous rachis (Chloridem).
 Spikelets with one fertile floret.
 Spikes racemose.
 1 Culms coarse, tufted, erect; panicles spikelike; ra-
 chilla not prolonged ......--- ....... -------------.... -- 15. Spartina
 Culms slender, erect or spreading; panicles open, the
 spikes spreading; rachilla prolonged.
 Spikes elongate, slender; spikelets comparatively
 distant __..... ... --.------.........----------.---.- 16. Gymnopogon
 ,Spikes short; spikelets crowded -... -... 18. Bouteloua