Plants in the genus Senna are shrubs, sometimes small trees or
perennialherbs. The leaves are arranged alternately,
paripinnate with up to 25 pairs of leaflets, each leaf with a
stipule at the base, but that often falls off as the leaves mature. The flowers are arranged in
racemes in leaf axils with
bracts at the base. The flower has five egg-shaped green or yellowish
sepals and five usually yellow, usually
glabrouspetals. There are usually ten
stamens that are free from each other, the
filaments of different lengths, and some are
staminodes. The fruit is a leathery
pod containing several seeds.[7][8][9][10]
Some species have
extrafloral nectaries on the leaves or flower stalks that are visited by ants.[4]
Pollination
Senna species are
pollinated by a variety of
bees, especially large female bees in genera such as Xylocopa.[4] They rely on "buzz pollination" and some within that on "ricochet pollination", which is a secondary pollen presentation where the pollen is not deposited on the pollinator's body by direct contact with the anthers.[18] The flowers have two sets of stamen: feeding stamens, which are longer, and pollinating stamens, which are smaller in size.[19] Due to buzz pollination, the pollens from the pollinating stamens get thrown from the anthers and ricochets against the petals multiple times before it settles on the dorsal side of the pollinating bee. The roughness on the petal walls causes the pollen to slow down its speed. The ricocheting effect alone cannot ensure effective pollen dissemination. It is aided by static charges wherein the flying bees become positively charged owing to the friction in the air and the pollen becomes negatively charged because of which they naturally get attracted to the bees body. The pollinator bee ends up carrying the pollen and also gets to feed on the pollen which is on the feeding stamens.[18]
Senna is considered to be a
bowel stimulant on the
myenteric plexus of the
colon to induce
peristaltic contractions and decrease water absorption from inside the colon, effects that would provide relief from
constipation.[21] The laxative
syrup of figs gets most of its effect from the presence of senna.[22]
Plants in the Senna genus have been studied for their beneficial effects arising from the abundance of phytochemicals, bioactive components and antioxidant and antimicrobial properties.[3]
Senna or its extracted
sennosides, alone or in combination with
sorbitol or
lactulose, have been evaluated in
systematic reviews and
Cochrane reviews for treatment of constipation in children and the elderly. Some studies showed limited evidence for efficacy,[23][24][25] whereas others indicated the study designs were too weak to be certain of senna having utility as a laxative.[21][26][27]
Fossil record
This section needs expansion. You can help by
adding to it. (April 2019)
^
abcdMarazzi, B.; et al. (2006). "Phylogenetic relationships within Senna (Leguminosae, Cassiinae) based on three chloroplast DNA regions: patterns in the evolution of floral symmetry and extrafloral nectaries". American Journal of Botany. 93 (2): 288–303.
doi:
10.3732/ajb.93.2.288.
PMID21646190.
S2CID24791422.
^Randell, B. R. and B. A. Barlow. 1998. Senna. pp 89-138. In: A. S. George (executive editor). Flora of Australia volume 12. Australian Government Publishing Service: Canberra, Australia.
^Huxley, A., et al. (1992). The New Royal Horticultural Society Dictionary of Gardening. The Macmillan Press, Limited: London. The Stockton Press: New York.
ISBN978-0-333-47494-5 (set).
^"Senna". Australian Biological Resources Study, Department of Agriculture, Water and the Environment: Canberra. Retrieved 3 June 2023.
^Jeanes, Jeff A.; Stajsic, Val.
"Senna". Royal Botanic Gardens Victoria. Retrieved 3 June 2023.
^Wiecek, Barbara.
"Senna". Royal Botanic Garden Sydney. Retrieved 3 June 2023.
^
abcLewis, G., et al. 2005. Legumes of the World. Royal Botanic Gardens, Kew: Richmond, England.
ISBN978-1-900347-80-8
^Irwin H. S., Barneby R. C. (1982). "The American Cassiinae: A synoptical revision of Leguminosae tribe Cassieae subtribe Cassiinae in the New World". Memoirs of the New York Botanical Garden. 35: 1–119.
^Singh, V. 2001. Monograph on the Indian Subtribe Cassiinae. Scientific Publishers (India): Jodhpur, India.
^The Fossil History of Leguminosae from the
Eocene of Southeastern North America by Patrick S. Herendeen, Advances in Legume Systematics: Part 4, The Fossil Record, Ed. P. S. Herendeen & Dilcher, 1992,
The Royal Botanic Gardens, Kew,
ISBN0 947643 40 0
Plants in the genus Senna are shrubs, sometimes small trees or
perennialherbs. The leaves are arranged alternately,
paripinnate with up to 25 pairs of leaflets, each leaf with a
stipule at the base, but that often falls off as the leaves mature. The flowers are arranged in
racemes in leaf axils with
bracts at the base. The flower has five egg-shaped green or yellowish
sepals and five usually yellow, usually
glabrouspetals. There are usually ten
stamens that are free from each other, the
filaments of different lengths, and some are
staminodes. The fruit is a leathery
pod containing several seeds.[7][8][9][10]
Some species have
extrafloral nectaries on the leaves or flower stalks that are visited by ants.[4]
Pollination
Senna species are
pollinated by a variety of
bees, especially large female bees in genera such as Xylocopa.[4] They rely on "buzz pollination" and some within that on "ricochet pollination", which is a secondary pollen presentation where the pollen is not deposited on the pollinator's body by direct contact with the anthers.[18] The flowers have two sets of stamen: feeding stamens, which are longer, and pollinating stamens, which are smaller in size.[19] Due to buzz pollination, the pollens from the pollinating stamens get thrown from the anthers and ricochets against the petals multiple times before it settles on the dorsal side of the pollinating bee. The roughness on the petal walls causes the pollen to slow down its speed. The ricocheting effect alone cannot ensure effective pollen dissemination. It is aided by static charges wherein the flying bees become positively charged owing to the friction in the air and the pollen becomes negatively charged because of which they naturally get attracted to the bees body. The pollinator bee ends up carrying the pollen and also gets to feed on the pollen which is on the feeding stamens.[18]
Senna is considered to be a
bowel stimulant on the
myenteric plexus of the
colon to induce
peristaltic contractions and decrease water absorption from inside the colon, effects that would provide relief from
constipation.[21] The laxative
syrup of figs gets most of its effect from the presence of senna.[22]
Plants in the Senna genus have been studied for their beneficial effects arising from the abundance of phytochemicals, bioactive components and antioxidant and antimicrobial properties.[3]
Senna or its extracted
sennosides, alone or in combination with
sorbitol or
lactulose, have been evaluated in
systematic reviews and
Cochrane reviews for treatment of constipation in children and the elderly. Some studies showed limited evidence for efficacy,[23][24][25] whereas others indicated the study designs were too weak to be certain of senna having utility as a laxative.[21][26][27]
Fossil record
This section needs expansion. You can help by
adding to it. (April 2019)
^
abcdMarazzi, B.; et al. (2006). "Phylogenetic relationships within Senna (Leguminosae, Cassiinae) based on three chloroplast DNA regions: patterns in the evolution of floral symmetry and extrafloral nectaries". American Journal of Botany. 93 (2): 288–303.
doi:
10.3732/ajb.93.2.288.
PMID21646190.
S2CID24791422.
^Randell, B. R. and B. A. Barlow. 1998. Senna. pp 89-138. In: A. S. George (executive editor). Flora of Australia volume 12. Australian Government Publishing Service: Canberra, Australia.
^Huxley, A., et al. (1992). The New Royal Horticultural Society Dictionary of Gardening. The Macmillan Press, Limited: London. The Stockton Press: New York.
ISBN978-0-333-47494-5 (set).
^"Senna". Australian Biological Resources Study, Department of Agriculture, Water and the Environment: Canberra. Retrieved 3 June 2023.
^Jeanes, Jeff A.; Stajsic, Val.
"Senna". Royal Botanic Gardens Victoria. Retrieved 3 June 2023.
^Wiecek, Barbara.
"Senna". Royal Botanic Garden Sydney. Retrieved 3 June 2023.
^
abcLewis, G., et al. 2005. Legumes of the World. Royal Botanic Gardens, Kew: Richmond, England.
ISBN978-1-900347-80-8
^Irwin H. S., Barneby R. C. (1982). "The American Cassiinae: A synoptical revision of Leguminosae tribe Cassieae subtribe Cassiinae in the New World". Memoirs of the New York Botanical Garden. 35: 1–119.
^Singh, V. 2001. Monograph on the Indian Subtribe Cassiinae. Scientific Publishers (India): Jodhpur, India.
^The Fossil History of Leguminosae from the
Eocene of Southeastern North America by Patrick S. Herendeen, Advances in Legume Systematics: Part 4, The Fossil Record, Ed. P. S. Herendeen & Dilcher, 1992,
The Royal Botanic Gardens, Kew,
ISBN0 947643 40 0