PDF - University Library

82 FIELDIANA: BOTANY, VOLUME 28
Dahlgrenia Steyermark, gen. nov.
Monoeca, spadicibus distinctis unisezualibus. Spadis utriusque
sexus ramosus, ramis masculinis tenuibus. Flores masculi minutuli:
calyx parvus, sepalls 3 imbricatis late subrhoraboideo-subglobosis;
corolla petalis 3 valvatis liberis non patentibus basi non-dilatatis
nee gibbosis oblongis; sta minibus 6. Flores foeminei parvi: calyx
sepalis 3 imbricatis suborbicularibus; corolla petalis 3 valvatis late
ovatis; staminodia 6 ad basim ovarii adhaerentibus; ovario integro
glabro, loculis 3, ovulo in loculo solitario, stigmatibus apicalibus.
Palmae inermes, frondibus paripinnatis. Pinnae apice praemorsae
et erosae.
Type species:
Dahlgrenia ptariana Steyermark.
This genus is dedicated to and named in honor of Dr. B. E.
Dahlgren, Curator Emeritus of the Department of Botany at the
Chicago Natural History Museum. Students of palms owe Dr.
Dahlgren a debt of gratitude for his contributions to the study of
tropical American palms, for the excellent series of palm exhibits
and palm herbarium which he has organized and developed at the
Museum, and especially for his monumental work "Index of American
Palms" published in 1936.
Dahlgrenia ptariana Steyermark, sp. nov.
Caudex 11-14 m. altus, 9.5-10 cm. crassus, solitarius; frondibus
2.2 m. longis 4-seriatis subcoriaceis supra viridibus infra argillaceis
lineis latis fuscis ad margines exteriores et squamis fuscis sessilibus
microscopic is obtectis; rhachi usque ad 4.5 cm. lata tomentosa
cinereo-fusca praedita supra carinata infra convexa; pinnis utroque
latere 28 valide sulcatis, pinna terminali cuneata praemorsa 50 cm.
longa, ceteris angustate ligulatis apice oblique praemorsis et erosis,
86-115 cm. longis, 7 cm. latis, infra usque ad 16 nervis, lineo lato
marginali 4-8 mm. lato; spathis elongatis; spadice masculina alba
ramis numerosis tenuibus 9-12 cm. longis, 2 mm. eras sis, glabris;
floribus masculinis confertis glabris; sepalis supra rotundatis 0.5
mm. altis, 0.7-0.8 mm. latis, petalis ovatis vel elliptico-oblongis,
0.7 mm. longis, 0.5 mm. latis, obtusis; antheris sessilibus vel fere
0.5-0.6 mm. longis; spadice foeminea alba tomentella pilis brevibus
albidis, rhachi 60 cm. longa, 1-2.5 cm. crassa, ramis numerosis 60
cm. longis, 2 mm. crassis; bracteis late ovatis acutis vel acuminatis,
2.5-3 cm. longis, basi 2 cm. latis, extus fulvo-tomentosis, intus
basi nigris; sepalis rotundatis 1.5 mm. altis, 2.5 mm. latis ad margines
ciliatis; petalis obtusis 2 mm. latis, 2 mm. altis, striatis;
staminodiis 0.2 mm. longis dentiformibus; ovario 1.2 mm. longo.
Fronds 4-ranked; rachis covered with a fine dull gray-brown
tomentum which wears off in age, but persists in places as a dark
brown tomentum; pinnae subcoriaceous, deep rich green above,
silvery below with a broad, dark brown, tomentose band extending
along outer margin on lower surface of each segment, sometimes