l - CNCFlora

Volume 91, Number 4
2004
Croat
Revision of Dieffenbachia
mary lateral veins 14 to 21 per side, departing mid- but flowering collections have also been seen in
rib at a mostly 30°-40° angle above middle, often September. Immature inflorescences have been
70°-90°, often arising at an acute angle, spreading seen from November to May, and mature fruits have
to the margins, broadly curved toward apex, even- been seen from the late rainy season (November)
tually merging at margins, weakly sunken above, to early rainy season (late June).
weakly convex below, drying brownish and darker Discussion. The species is characterized by its
than surface below; the interprimary veins usually fully sheathed petioles, involute petiolar sheath,
darker than surface, 1 between each pair of primary and by its thick and more or less elliptic, semilateral
veins; minor veins visible, slightly darker glossy to glossy, mostly unvariegated blades that
than surface, drying moderately obscure on lower dry somewhat greenish to yellow-brown.
surface. INFLORESCENCES 3 to 6 per axil; pe- Dieffenbachia horichii is closely related to two
duncle 8.5-19 cm long (averaging 13.5 cm), 3-6 other species with petioles fully sheathed or nearly
mm diam., drying striate; spathe 14.5-32.5 cm so. These are D. panamensis and D. standleyi. In
long, 4-5.5 cm diam. (averaging 20.8 cm long), comparison with D. horichii: D. panamensis has
2.5-4 cm diam. at constriction, 0.9-2.3 times lon- similarly shaped blades and petioles fully sheathed,
ger than the peduncle (averaging 1.5 times longer but that species differs in having the petiole sheath
than the peduncle), gradually long-tapered toward usually flaring and recurled rather than involute as
apex from midway, light green to medium green in D. horichii. It also has leaf blades with the upper
throughout; spathe tube 3 x 2.3 cm diam. when surface matte and subvelvety that dry blackened.
furled (flattening 4.0-5.5 cm wide), the constricted Another difference is that D. panamensis occurs
area flattening 2.5-4.0 cm wide; spathe blaele 2.5- principally on the Atlantic: slope of central Panama,
4 cm wide at anthesis; spadix 13-27 cm long (av- whereas D. horichii occurs on the Pacific slope of
eraging 17.4 c m long); free portion 10-13.5 ( m Costa Rica.
long; pistillate portion to (6.5)8-10.8 cm long (av- DieJ/en/)lchi(l horichii is likely to I)e (onfuse(l
eraging 8.3 c m long), 8-17 mm wide, drying 8 mln with D. .st(ln(lleyi: another sr)ee ies with fully or
diam.; feltile staminate )ortion 8. 3-12 cm long, mostly winpr,(l Xetioles. That sI)ee ies oe ( urs; on the
c rearm-( olore(le mo(lerately tapere(l towar(l aI)ex an(l Atlantie slole of Hon(luras an(l Nie arapr,ua, an(l (lifweakly
talxere(l towar(l baxe, 7-12 mln (liam. mi(l- fers lxy 11avinpr, the [)etiole slleatll eree t an(l re( urle(l
way; mostly xtel ile interlne(liclte segnlerlt 1 .7--3.7 outwar(l alont, the margins an(l a(ute at the ay)ex
cm long, witll a few xcattele(l xtamino(lia through- with the sheath margins marke(lly un(lulate (vs. tlle
out; pixtilx 4.-3 to 69, irregulal Iy scattere(l, neal Iy sheath malgins illvolute an(l smooth). 'I'he letioles
contiguouse .-3 to 4(6 to 7) (lisl)erse(l acloxs xla(lix of l). .ft(lMdleyi are also longer on average, frequentwidth?
xelalate(l from one another by ul) to 4 tinlex ly more than 25 c m long, an( average 3() (m long
their width; ovary depresse(l-globoxeX 2 mm long, (vs. fre(uently 1ess than 25 c rll long, averaging less
yellow-green; xtigma cushion-S;hape(l, 2.8-3.4 mm than 2() ( m long for l). horichii). Tn a(i(itionX the
diam., about twice as wide ax thick and usually upper midrib on the l)lades of D. stclol(lleyi is broa(lbroader
than the pistil at anthesix, yellowish; xta- ly concave, whereas on D. horichii the midril) is
minodia white, 3 to 5 per pistil, 3-4 mm long, free l)roadly (onvex with a medial sulcus lout with the
or briefly united at base; synan(lria 1.6-3.0 mm entire midrib sunken in a valley.
diam., subrounde(l, depressed medially at apex, Most of the typical material of D. stan(lleyi has
drying orange-brown. INFRUCTESCENCE 19-24 been collected in the Lancetilla Valley and its vicm
long; spathe orange outsi(le; spadix 8-15 cm cinity in HoncAllras, and has blades considerably
long; berries red, subglobose, ovoid to ellipsoid, 7- longer on average than those of D. horichii. Some
10 mm long.
collections in Nicaragua and in western Costa Rica
are unusual. Stevens 7457 from Zelaya and Moreno
Distribution and habitat. Dieffenbachia horichii 17142 from Matagalpa dry a darker yellow-brown.
is known only from the Pacific slope of Costa Rica The only other species in Central America that has
from the Carara reserve and Puriscal region to the a fully sheathed petiole is D. tonduzii. Dieffenbach-
San Isidro region and Dominical. It occurs in Pre- ia tonduzii is distinguished by having smaller and
montane rain forest (P-rf) and transition forests be- thinner blades (rarely to 45 cm long and 20 cm
tween Tropical wet forest (T-wf) and Premontane wide) that are usually matte to weakly glossy above
rain forest (P-rf) life zones (Holdridge, 1967), from (vs. usually glossy in D. horichii) with more primary
sea level to 900 m.
lateral veins (18 to 25 vs. usually fewer than 20 in
Phenology. Dieffenbachia horichii begins to D. horichii). Grayum 4757: from the Carara Reflower
in the early rainy season from May to July, serve in Puntarenas Province, is perhaps a hybrid
717