Important Trees of Haiti

14 Kasya
Species: Senna siamea (Lam.) Irwin & Barneby
Synonyms: Cassia arborea Macfad., C. florida Vahl, C. gigantea Bertero, C. siamea
Lam., Sciacassia siamea (Lam.) Britton
Family: Fabaceae (=Leguminosae) Subfamily: Caesalpinioideae
Common Names: H - casse de Siam, cassia (kasya); RD - acacia amarilla, casia de
Siam, flamboyan amarillo, la casia amarilla; C, PR - casia, casia siamea; J, PR,US ­
kassod-tree, Siamese senna, Siamese shower.
Importance: There are several reasons that Senna siameabecame one ofthe most popular
species ofthe Haitian farmer. It grows fast on a wide range ofsites to provide quick
shade and a moderately dense wood for small timber and fuelwood. It coppices well to
yield successive crops. It is not weedy and generally is refused by animals as a browse.
The crown is erect and the seedling is more shade tolerant than most other fast-growing
exotics. It fits well into the traditional lakou system, besides being suitable for
hedgerows, boundary plantings, and woodlots.
Taxonomy and Botanical Features: The species first was described in Thailand, formerly
Siam, as the common and scientific names indicate. A major revision of the
Cassieae tribe distinguishes three closely-related genera (Cassia, Senna and
Chamaecrista) based on the stamen and bract features (Irwin and Barneby, 1982). The
medium-sized tree is recognized by the large terminal clusters ofshowy yellow flowers
and numerous bunches of flat, narrow, slightly curved, dark brown pods which split
open to release more than a dozen shiny, circular, dark brown, flat seeds 8 mm indiameter
(Fig. 14.1 inset). The 6-14 paired leaflets, 3-7.5 cm long and 1.3-2.3 cm wide, are
attached to a reddish tinged axis and have a dark green upper surface and a gray green
lower surface. The flower stalks and new growth have a yellowish tint.
Distribution and Ecology: The natural range of the species is southeast Asia from
southern India to the Malay peninsula. It has been planted throughout the tropics as a
fast-growing reforestation species and the time ofits entry to Haiti is uncertain. Little
and Wadsworth (1964) reported the species' introduction to Jamaica prior to 1837.
SHADA planted the species in the Bayeux and Franklin areas in the 1940s. As the
most-planted species during the USAID Agroforestry Outreach Project (1981-1989)
and Agroforestry II (1990-1991), the gene pool, mostly from the Bayeux population,
has been distributed throughout Haiti. The main distribution ofthe species still is centered
along travel ways, commonly occurring as a combination ornamental, boundary
planting, and shade tree in the residential sections of small towns. During 1988, additional
seed lots were imported from Central America and Africa and were incorporated
into a program to broaden the genetic base ofthe species and to begin selection ofsuperior
trees.
The tree prefers elevations under 500 m and annual rainfall amounts from
1000-2000 rom. It fails on sites with a combination ofalkaline soils, particularly heavy
clays, and 4-5 months ofdrought with no access to deep soil moisture. It survives poorer
than Leucaena leucocephala ssp. glabrata and Azadirachta indica on shallow and
rocky soils. The tree tolerates the poorly-drained vertisols, but prefers the sandy loams
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