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160 FIELDIANA: BOTANY, VOLUME 28
crest of cerro between east and west end, Sororopan-tepui, state of
Bolivar, alt. 2255 m., November 14, 1944, Julian A. Steyermark
60124 (staminate plant); same locality Steyermark 60143 (pistillate
plant), co-type.
By having the seeds winged all around, this species would fall
into subgenus Eudioscorea, according to R. Knuth's treatment of the
genus in "Das Pflanzenreich". It is characterized by the 3 short
fertile stamens without staminodia in the staminate flowers, the
broadly suborbicular, rounded or obtuse staminate perianth segments,
the fasciculate, sessile staminate flowers, the capsule as broad as
or slightly broader than long, and the relatively small, broadly ovate,
heart-shaped leaves with a conspicuous reticulum of nerves beneath.
It may be considered a member of the sect. Hemidematostemon
Griseb., the known species of which are all Brazilian, but does not
agree with any of the described species of that section.
IRIDACEAE
Trimezia Fosteriana Steyermark, sp. nov.
Herba perennis, ex cormum oriunda; scapo erecto subcomplanato
simplici glabro, 60-75 cm. alto, bi- vel tri-foliato, bracteis subfoliosis
remotis, 5 - 13 cm. longis; foliis radicalibus elongatis erectis
glauco-viridibus subcoriaceis conspicue striatis linearibus, 30-65
cm. longis, 5-8 mm. latis, apice obtusis et asymmetric is; spatha
terminali sessili 1-3-flora bivalva; valvis inaequalibus pedicellum
subaequantibus striatis late lanceolatis carinatis 3.5-4.5 cm. longis,
8-10 mm. latis, acutis vel acuminatis, exteriore interiorera basi
amplectenti; floribus aureo-purpureo-maculatis; perigonii laciniis
2.5 cm. longis, exterioribus patentibus, interioribus minoribus sursum
arcuatis; stylo 13 mm. longo trigono tripartite, laciniis triangulatis
aureo-flavidis 4 mm. longis, uno angulo ad duas margines late
alato; stigmatibus bifidis lobatis vel crenatis, dentibus obtusis;
staminibus styli ramulis oppositis et adnatis; filamentis liberis
aureo-flavidis 4 mm. longis; antheris 6 mm. longis, apice apiculatis,
juxta longitudinem dehiscentes; ovulis in loculis plurimis.
Type in herb. Chi. Nat. Hist. Mus., collected along Rio Tek-
Yunsen, between Santa Teresita de Kavanaye'n and Carrao-tepui^
state of Bolivar, alt. 1375 m., December 4, 1944, Julian A. Steyermark
60834; sandy wet ground with Stegolepis and Brocchinia, Gran
Sabana, between Mission of Santa Teresita de Kavanayen northwest
to Rio Karuai, on large mesa, state of Bolivar, alt. 1220 m., October
26, 1944, Steyermark 59364.
This species is named in honor of Dr. Robert C. Foster of the
Gray Herbarium of Harvard University. His studies of tropical
American Iridaceae in recent years have done much to further our
taxonomic knowledge of this family.