Amorphophallus titanum, the Titan Arum, is the species of plant which is known to produce the world’s largest unbranched inflorescence. On March 5, 2011 in the oldest greenhouse of Department of Biological Sciences the first of two 10 year-old seedlings given to us by Mo Fayyaz of the University of Wisconsin came into flower.
Although this aroid is uncommon in the wild, occurring only in gaps and edges of the western tropical rainforest in Sumatra (Brown 2000), it has been brought into cultivation in botanical gardens, conservatories and university plant collections. In the last 2 decades blooming plants of this species have frequently attracted thousands of visitors and much curiosity among its observers (Wikipedia).
The blooming Titan Arum provides a sensory experience unlike any commonly known to the public. The bloom (inflorescence) is usually solitary, tall (from 3 to 11 feet tall: ours was 4ft) and appears out of bare soil, emerging as a small bud (image 1 MONTAGE) and finishing a month later as a striking, stinking, pleated swirl of deep dusky blood-colored spathe unfurling around the pale, erect, rumpled spadix (images 3-5). The spathe opens from a tight wrap around the spadix (image 2) to a full skirt over a period of about 12 hours. The bloom emits pulses of odor in late evening, akin to rotting flesh (Barthlott et al 2008), synchronous with increased temperature of the spadix tip (max. 98F in our plant) and base (max. 81F), where the true flowers are hidden.
Those true flowers consist of individual pistils (female) and individual stamens (male). The female flowers occur in a band below the male band (images “window, 7-20 MONTAGE), and are receptive the day before males shed their pollen, preventing self-pollination (Brown 2000). Pollinators in the wild are reportedly carrion and dung beetles (Gandawijaja et al 1983).
The recent increase in the numbers of this species in cultivation provides an opportunity to investigate topics of inquiry ranging from quantitative trait studies to genetic diversity and inbreeding depression in an uncommon tropical plant. To that end we have collected and dispensed pollen to other institutions with mature-sized plants. We hope to apply the remaining pollen to the second seedling, a sibling of our first (“Tatiana, the Titan Princess”), when it also comes into bloom. Tatiana’s first bloom now resides in the collection as a specimen for study in the herbarium of the Section of Botany at the Carnegie Museum of Natural History here in Pittsburgh.
For a photographical journey through our 2011 Amorphophallus titanum bloom, see the montage and links to enlarged versions of each photo below:
- The flowering bud and a small leaf bud Feb 3 2011
- The flowering bud Mar 3, 2011
- Tatiana the Titan Princess in all her glory, at about 9:30 PM March 5, 2011
- View into the spathe, to see the base of the spadix, where the band of female flowers is found
- Another view of the whole inflorescence. At this point the tip of the spadix was 98oF, the midpoint was 77oF and the base was 81oF.
- March 6, 2011, 10AM
- Enlarged view of a style and stigma of one female flower
- Enlarged view of a group of female flowers
- On March 9 we cut a window in the base of the spathe in order to gain access to the male and female flowers for pollen collection and imaging
- A cluster of the male flowers
- Three of the male flowers enlarged
- Longitudinal section through a female flower
- Base of the female flower.
- Base of the style in the female flower
- (SEM) Three male flowers
- Closer look at one male flower with 2 pores through which pollen is extruded
- (SEM) Pore in male flower through which pollen is extruded, with pollen visible in the pore
- (SEM) Base of the female flower.
- (SEM) Base of the style in the female flower
- (SEM) Pollen grains visible at the pore in the male flower
- The window cut in the base of the spathe to reveal the female flowers embedded in the base of the spadix and the male flowers above.
Plant Growth Facilities Manager
Scanning Electron Microscopy and Photos:
Tom Harper, Microscopy and Imaging Facility Director
Barthlott, W., J. Szarzynski, P. Vlek, W. Lobin, N. Korotkova (2009). "A torch int eh rain forest: thermogenesis of the Titan arum (Amorphophallus titanum)." Plant Biology 11: 499-505
Brown, D. (2000). Aroids. Portland Oregon, Timber Press.
Gandawijaja, D., S. Idris, R. Nasution, L.P.Nyman, J. Arditti (1983). "Amorphophallus titanum Becc. : a historical review and some recent observations." Annals of Botany 51: 269-278.
Wikipedia. "List of publicised titan arum blooms in cultivation."