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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, 28 Sept. 2018, No. 2 
5a. Inflorescence rachis, peduncles, and pedicels glabrous; calyx lobes linear to 
lance-linear, 3-5 mm wide; corolla 35^10 mm long; stamens 55-77 mm long, 
thecae 6.5-9.5 mm long; capsules glabrous; Belize. L. chartaceum 
5b. Inflorescence rachis, peduncles, and pedicels pubescent with eglandular tri- 
chomes; calyx lobes ovate-elliptic to elliptic to obovate, 9-15 mm wide; 
corolla 50-55 mm long; stamens 72-90 mm long, thecae 10-12 mm long; 
capsules pubescent; western Mexico (Jalisco and Michoacan). L. koelzii 
lb. Stamens 2; leaves ± evenly distributed along young stems, not all seasonally deciduous (i.e., 
plants never entirely leafless); occurring in moist to wet forests. 
.Sects. Louteridium and Parcostamium 
6a. Leaf blades oblanceolate to obovate; inflorescence appearing conspicuously dichotomous- 
ly branched; bracteoles of a pair connate along one side for up to 1/2 their length and sub- 
saccate at base; posterior lobe of calyx subsaccate or with a flap-like appendage at base; 
corolla externally glabrous; capsule glabrous; Mexico. L. parayi 
6b. Leaf blades cordate to ovate to broadly ovate to elliptic to broadly elliptic to obovate; inflo¬ 
rescence not appearing dichotomously branched; bracteoles neither connate nor subsaccate; 
posterior lobe of calyx not subsaccate/appendaged at base; corolla externally pubescent; 
capsule pubescent (glabrous in L. costaricense ); Mexico and Central America. 
7a. Bracts persistent during flowering; capsule glabrous, stipe 7-12 mm long; southern 
Central America (Costa Rica and Panama). L. costaricense 
7b. Bracts caducous during flowering (or sometimes proximal bracts persisting in 
L. donnell-smithii ); capsule with sessile or stipitate glands, stipe 1-4 mm long; Mexi¬ 
co and northern Central America. 
8a. Leaves subsucculent; posterior calyx lobe planar; style 48-73 mm long, seeds up 
to 20 per capsule; northeastern Mexico (Tamaulipas). L. tamaulipense 
8b. Leaves membranaceous; posterior calyx lobe conduplicate; style 72-92 mm long; 
seeds up to 16 per capsule; southern Mexico, Belize, Guatemala, and western Hon¬ 
duras.Sect. Louteridium 
9a. Young stems and leaves densely pubescent with erect to flexuose eglandular 
trichomes to 2 mm long; inflorescence peduncles and rachis, flower pedicels, 
and abaxial surface of calyx pubescent with glandular and eglandular 
trichomes to 2.8 mm long (viscid); leaf margin crenate-dentate. 
. L. donnell-smithii 
9b. Young stems and leaves glabrous or pubescent with erect, flexuose, retrorse, 
or antrorse eglandular trichomes < 0.05-0.5 mm long; inflorescence peduncle 
and rachis, flower pedicels, and abaxial surface of calyx glabrous or pubescent 
with eglandular trichomes < 0.05-1 mm long; leaf margin entire to crenate 
(sometimes to crenate-dentate in L. mexicanum). 
10a. Rachis glabrous or pubescent with flexuose to flexuose-antrorse 
trichomes 0.2-1 mm long (villous); pedicels glabrous or villous; abaxial 
surface of calyx either appearing glabrous (although covered with glan¬ 
dular punctations < 0.05 mm in diameter) or villous along keel; capsule 
sparsely puberulent with sessile to subsessile glands to 0.05 mm long; leaf 
blades broadly ovate to ovate to elliptic to broadly elliptic; Gulf of 
Mexico and Caribbean Sea versants. L. mexicanum 
