السيكاسية
Cycadophyta Temporal range: Early Permian-Recent PreЄ
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Cycas rumphii with old and new male cones. | |
التصنيف الفهمي | |
مملكة: | Plantae |
Division: | Cycadophyta |
Class: | Cycadopsida |
Order: |
Cycadales Dumortier |
Families | |
Cycadaceae cycas family |
السـِّـيكاسية Cycad نبتة تنموفي المناطق الاستوائية (المدارية)، وشبه الاستوائية من العالم، شبيهة بالنخل أوالسّراخس الشجرية، وهي من عاريات البذور، وقد يصل طولها إلى 20م.
وهناك نحو100 نوع منها ولبعضها جذور درنية شبيهه بالبطاطس. وقد عثر الفهماء على سيكاسيات عمرها أكثر من 1,000 سنة. ولأغلب السيكاسيات مخاريط تحمل البذور. وتنموالمخاريط وسط مجموعات أوراق النبات. وعندما تنضج البذور، فإنها تتساقط من المخروط على الأرض.
والسيكاسيات نباتات قديمة كانت تعيش في حقب الحياة الوسطى، أي قبل 240 – 63 مليون سنة. وهي الأنواع المتبقية من مجموعات كانت واسعة الانتشار. وهي مبعثرة التوزيع وتوجد أكثر أنواعها في الأمريكتين (بما فيها فلوريدا). وتوجد في أستراليا وجنوب إفريقيا مجموعة واسعة من الأنواع، وتغرس السِّيكاسيات نباتات للزينة. وتقابل بعض الأنواع خطر الانقراض بسبب الإفراط في جمعها.
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وجهة النظر التقليدية | وجهة النظر المعاصرة |
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التاريخ
التوزيع
البساتين
انظر أيضا
- Fossil Cycad National Monument
المصادر
- الموسوعة المعهدية الكاملة
- Chamberlain, C.J. (1965) [1919] The Living Cycads, 1st ed. reprinted, New York : Hafner, 172 p., LCCN 65-027079
- Chaw, S.-M., Parkinson, C.L., Cheng, Y., Vincent, T.M., & Palmer, J.D. (2000) "Seed plant phylogeny inferred from all three plant genomes: Monophyly of extant gymnosperms and origin of Gnetales from conifer", Proceedings of the National Academy of Sciences, 97 (8), p. 4086-4091.
- Chaw, S.-M., Walters, T.W., Chang, C.-C., Hu, S.-H., & Chen, S.-H. (2005) "A phylogeny of cycads (Cycadales) inferred from chloroplast matK gene, trnK intron, and nuclear rDNA ITS region", Molecular Phylogenetics and Evolution, 37 (1), p. 214-234. DOI:10.1016/j.ympev.2005.01.006
- Chaw, S.-M., Zharkikh, A., Sung, H.-M., Luu, T.-C., & Li, W.-H. (1997) "Molecular phylogeny of extant gymnosperms and seed plant evolution: Analysis of nuclear 18s rRNA sequences", Molecular Biology and Evolution, 14 (1), p. 56-68.
- Crepet, W.L. (2000) "Progress in understanding angiosperm history, success, and relationships: Darwin's abominably 'perplexing phenomenon'", Proceedings of the National Academy of Sciences, 97 (24), p. 12939-12941, DOI:10.1073/pnas.97.24.12939
- De Luca, Paulo (1990) "A Historical Perspective on Cycads from Antiquity to the Present", In: Stevenson, D. (Ed.) The Biology, Structure, and Systematics of the Cycadales, Memoirs of the New York Botanical Garden, 57, p. 1-7, ISBN 0-89327-350-3
- Donaldson, J.S. (2003) "Chapter 3: Regional Overview: Africa", In: Donaldson, J.S. (ed.), Cycads. Status Survey and Conservation Action Plan, IUCN/SSC Cycad Specialist Group, Gland; Cambridge : UKIUCN, ISBN 2-8317-0699-8, p. 9-19
- Donaldson, J. (2004) "Saving ghosts? The implications of taxonomic uncertainty and shifting infrageneric concepts in the cycadales for red listing and conservation planning", In: Walters,T. & Osborne, R. (eds), Cycad Classification: Concepts and Recommendations, Wallingford, UK : CABI, ISBN 0-85199-741-4, p. 13-22.
- Donaldson, J., Hill, K.D., & Stevenson, D.W. (2003a) "Chapter 2: Cycads of the World: An Overview", In: Donaldson, J.S. (ed.), Cycads. Status Survey and Conservation Action Plan, IUCN/SSC Cycad Specialist Group, Gland; Cambridge : UKIUCN, ISBN 2-8317-0699-8, p. 3-8
- Donaldson, J.S., Dehgan, A.P., Vovides, A.P., & Tang, W. (2003b) "Chapter 7: Cycads in trade and sustainable use of cycad populations", In: Donaldson, J.S. (ed.), Cycads. Status Survey and Conservation Action Plan, IUCN/SSC Cycad Specialist Group, Gland; Cambridge : UKIUCN, ISBN 2-8317-0699-8, p. 39-47
- Golding, J.S. & Hurter, P.J.H. (2003) "A Red List account of Africa’s cycads and implications of considering life-history and threats", Biodiversity and Conservation, 12 (3), p. 507–528, DOI:10.1023/A:1022472801638
- Gonzàlez-Astorga, J., Vovides, A.P., Ferrer, M.M., & Iglesias, C. (2003a) "Population genetics of Dioon edule Lindl. (Zamiaceae, Cycadales): biogeographical and evolutionary implications", Biological Journal of the Linnean Society, 80 (3), p. 457-467, DOI:10.1046/j.1095-8312.2003.00257.x
- Gonzàlez-Astorga, J., Vovides, A.P., & Iglesias, C. (2003b) "Morphological and geographic variation in Dioon edule Lindl. (Zamiaceae): ecological and evolutionary implications", Botanical Journal of the Linnean Society, 141 (4), p. 465-470, DOI:10.1046/j.1095-8339.2003.00155.x
- Gregory, T.J. & Chemnick, J. (2004) Hypotheses of the relationship between biogeography and speciation in Dioon (Zamiaceae). In: Walters,T. & Osborne, R. (eds), Cycad Classification: Concepts and Recommendations, Wallingford, UK : CABI, ISBN 0-85199-741-4, p. 137-148.
- Hill, C.R. (1990) "Ultrastructure of in situ fossil cycad pollen from the English Jurassic, with a description of the male cone Androstrobus balmei sp. nov.", Review of Palaeobotany and Palynology, 65 (1-4), p. 165-193, DOI:10.1016/0034-6667(90)90067-S
- Hill, K.D. (2003) "Chapter 4: Regional Overview: Australia", In: Donaldson, J.S. (ed.), Cycads. Status Survey and Conservation Action Plan, IUCN/SSC Cycad Specialist Group, Gland; Cambridge : UKIUCN, ISBN 2-8317-0699-8, p. 20-24
- Hill, K.D. (2004) "Character evolution, species recognition and classification concepts in the cycadaceae", In: Walters,T. & Osborne, R. (eds), Cycad Classification: Concepts and Recommendations, Wallingford, UK : CABI, ISBN 0-85199-741-4, p. 23-44. CABI, Oxford.
- Hill, K.D., Stevenson, D.W., & Obsorne, R. (2004) "The World List of Cycads", Botanical Review, 70 (2), p. 274-298. DOI:[0274:TWLOC2.0.CO;2 10.1663/0006-8101(2004)070[0274:TWLOC]2.0.CO;2]
- Jones, David L. (1993) Cycads of the World, Washington, D.C. : Smithsonian Institution Press, ISBN 1-56098-220-9. 2nd ed. republished (2002) as: Cycads of the World: ancient plants in today's landscape, Sydney : Reed New Holland, ISBN 1-876334-69-X
- Keppel, G., Lee, S.W., & Hodgskiss, P.D. (2002) " A.Br. (Cycadaceae)", Journal of Heredity, 93 (2), p. 133-139. DOI:10.1093/jhered/93.2.133
- Norstog, K.J. & Nicholls, T.J. (1998) Biology of Cycads, Ithaca : Cornell University Press, ISBN 0-80143-033-X
- Walters, T., Osborne, R., & Decker, D. (2004) "We hold these truths…", In: Walters,T. & Osborne, R. (eds), Cycad Classification: Concepts and Recommendations, Wallingford, UK : CABI, ISBN 0-85199-741-4, p. 1-11
- Whitelock, L.M. (2002) The Cycads, Portland, OR : Timber Press, ISBN 0-88192-522-5
وصلات خارجية
مشاع الفهم فيه ميديا متعلقة بموضوع Cycadophyta. |
- Palm Trees, Small Palms, Cycads, Bromeliads and tropical plants site with thousands of large, high quality photos of cycads and associated flora. Includes information on habitat and cultivation.
- Hill KD (1998-2004) The Cycad Pages, Royal Botanic Gardens Sydney. http://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/index.html
- Gymnosperm Database: Cycads
- Fairchild Tropical Botanic Garden- one of the largest collection of cycads in the world in Florida, U.S.A.
- Palm and Cycad Societies of Australia (PACSOA)
- The Cycad Society of South Africa
- Cycad nitrogen fixation
- Cycad toxicity
- Cycads - Foto
- , New York Times Magazine article on cycad collectorship and cycad smuggling
- Cycads An annotated link directory