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Dracontium Inflorescences
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Dracontium inflorescences
are produced in advance of, or sometimes after, new leaf development. When
the inflorescence is produced right after a new leaf, it often appears as
developing simutaneously with the leaf (as sometimes in D. croatii, D. pittieri
and D. spruceanum). Each inflorescence consists of three to five bracteoles
and a pedunculate spathe enclosing a sessile or stipitate spadix and 3-5 bracteoles.
Peduncle. The peduncles of Dracontium are usually much shorter and thinner
than the leaf petioles (
Fig. 26 ), rarely exceeding the petiole (as sometimes in D. spruceanum).
They range from barely reaching or slightly surmounting ground level (D. changuango,
D. purdieanum, D. soconuscum and D. ulei) to almost as long as the petiole
(D. spruceanum and D. pittieri). The peduncles are anatomically identical
to the petioles. The peduncles are much like the petioles in terms of coloration
and armament, but tend to be smoother, and sometimes tinged more rose or brown.
Spathe. The shape and size of the
spathe constitute the most important characters for species distinction in
Dracontium. The spathe is marcescent and often disintegrates on developed
infructecence. At anthesis, the length of the spathe in the genus ranges from
a couple of centimeters long and 1 cm wide (as sometimes in D. bogneri) to
85 cm long and 20 cm wide (D. gigas). Spathes may be more or less hooded and
boat-shaped (D. gigas, D. pittieri and D. asperum) or suddenly contracted
at a certain point and gradually acuminate distally (D. changuango, D. purdieanum,
D. spruceanum and D. angustispathum). The spathe margins may be broadly overlapping
near the base forming a bell- shaped tube and broadly open above (D. soconuscum,
D. purdieanum, and D. grayumianum); broadly overlapping in the lower 1/3 to
2/3 with a narrow opening above (D. gigas and D. prancei); or barely overlapping
(D. polyphyllum and D. pittieri). The apex of the spathe is narrowly or broadly
acuminate and ranges from erect or slightly arching (less than 45E, D. angustispathum,
D. spruceanum, and D. polyphyllum) to strongly arching (from 45E to 90E, as
in D. asperum and D. amazonense).
The outer surface
of the spathe is often matte, with many elongate clumping projections (
Fig. 42-45 ). It may be maroon tinged green (D. spruceanum), purplish-red
or olive-brown (D. polyphyllum), or green (D. croatii and sometimes D. spruceanum)
or sometimes with a paler area at the base on the abaxial side (D. asperum).
The inner surface of the spathe may be glossy (D. plowmanii, Fig. 43; D. angustispathum,
Fig. 47) or semiglossy (D. pittieri, Fig. 48 and D. gigas, Fig. 49) or covered
with dense, transparent scales (D. purdieanum, Fig. 50 and D. changuango,
Fig. 51). The inner surface is maroon (D. polyphyllum) or maroon tinged reddish
(D. asperum and D. soconuscum) or reddish-brown to olive-brown (D. spruceanum).
There is usually a creamy-white basal translucent area which may be obscure
(D. asperum, D. polyphyllum and D. ulei) or to 1-3 times as long as the spadix
(D. pittieri, D. spruceanum, D. asperispathum and D. grandispathum). The inner
surface of the spathe often has whitish or brownish spotted gland-like stomatal
structures all over (Fig. 52-53). These control the emission of scent (see
section on Phenology and Pollination).
Spadix. The spadix of Dracontium
is sessile, or on a stipe to 0.5- 2.5 cm long. It ranges from 1-9 cm long
and 0.5-2 cm diam. at anthesis, and from 4-25 cm long and 4-10 cm diam. when
fruiting. The color of the spadix is the color of the tepal apices and styles,
which may be dark purple, green, light brown, or rarely gray. The spadix may
be hidden at anthesis (D. gigas, D. spruceanum and D. asperum) or exposed
naturally (D. polyphyllum, D. pittieri, D. soconuscum, D. purdieanum, and
D. changuango). They are typically cylindric (
Fig. 54 ), rarely globose or sometimes cylindroid-tapered (
Fig. 55-56 ). Sometimes 1-5 tepals of the flowers at the apex of the spadix
are elongated and enlarged becoming 0.5-1 cm long appendages (D. changuango,
D. grayumianum, D. purdieanum and D. soconuscum, (
Fig. 57 ). The function of these appendages is unknown. The axis of the
spadix consists of aerenchyma cells (Fig. 58- 59), similar to those of the
petioles and peduncles.
