Nicotiana tabacum Falak Bhatt IB 423 May 4, 2005 www.plantoftheweek.org

Classification Division Magnoliophyta Class: Magnoliopsida Order: Solanales Family: Solanaceae Genus: Nicotiana Dicot http://www.landlfinecigars.com

History Indigenous to North and South America 1 BCE: Experts believe American inhabitants have begun finding ways to use tobacco, including smoking and chewing Native Americans smoked before Europeans arrived in America, gave dried leaved as gift to Columbus Settlers brought habit back to Europe U.S. early colonies made most of internal revenue from tax of tobacco export Say about different ways smoking was done…fires tobacco leaves dried, smoked with other leaves http://www.research.att.com www.tobacco.org

Root Hair (w/ trichoblast) Dicot-Open Root System, Fibrous Root Hair (w/ trichoblast) Rhizodermis Apical Meristem Restate difficulty of exact locations b/c of whole mount and small size of roots. Mention where vascular cylinder is…look at pg 3 of lab 11. Say where zones are pg 3 lab 11. mention total root length varied from widely with longest reaching 25inches. Root Cap Columella Root tip 10x-TOL B

Root Tetrarch development Phloem Xylem Pericycle Root stele has tetrarch development. Exarch young cells on inner part-centripetal. lab 11. endodermis ripped off Pericycle Root xs 20x Phloro.

Root: Secondary Growth Ray Secondary Xylem Root xs 10x TOL B Primary Xylem Root xs 4x TOL B

Root Vascular Tissue Trichome Whole root 10x TOL B

Continuous vascular tissue Stem Bicollateral phloem Continuous vascular tissue Crang and Vassilyev Cortex- Parenchyma External Phloem Vascular Cambium Xylem Internal Phloem cambium produces a continuous cylinder of secondary vascular tissues. Note the strands of internal phloem around the periphery of the pith marking the location of vascular bundles prior to stem secondary thickening. The internal phloem is preserved in its primary state because no vascular cambium is produced between it and the internal portion of primary xylem. Although internal phloem may be found in economically important plants, it is not the typical vascular pattern among angiosperms. Tobacco stem: Continuous vascular cylinder is derived from cambium No isolated vascular bundles No secondary growth of internal phloem Pith Stem xs 10x

Multicellular, uniseriate trichomes Stem Multicellular, uniseriate trichomes Trichomes Stem xs 20x Name all the parts again…pith, parenchyma phloem. But Point out the trichomes and epidermis. Trichomes cover all of plant Epidermis Stem xs 10x

Next up…Leaves Bifacial Reticulate (netted) venation-Dicot Trichomes http://www.botgard.ucla.edu Reticulate (netted) venation-Dicot Trichomes Trichomes cover leaves and all surfaces. Palisade has cholorplasts…unstained leaf looks green like above. Bifacial is also called dorsiventral Palisade Mesophyll Spongy Mesophyll Leaf xs 10x

Leaves Abaxial Adaxial Amphistomatic Simple Leaf peel 20x Leaf peel 20x Simple- single blade w/ petiole (stalk and major vein). Point out how there is no pattern in stomata, that’s why it is anomocytic. Some perpendicular surrounding cells, some parallel, sometimes 3, sometimes 4 surrounders. Abaxial Adaxial Amphistomatic Simple Anomocytic stomatal arrangement

Major Leaf Vein…Bicollateral view Leaves Major Leaf Vein…Bicollateral view Phloem Vascular Cambium Xylem Phloem

Leaves: Gap and Trace Outer endodermis Inner endodermis Stem xs 10x Mention trichomes still visible. Pith, outer and inner endodermis. Stem xs 10x Leaf trace Leaf gap

Reproductive Structures Optional Features Reproductive Structures Ovules Locules Ovary longitudnal Ovary Wall Sepal Ovule Locule Bud xs

Reproductive Structures Endosperm Testa Integument will become seed coat. embryo is surrounded by three to five layers of rather thick-walled endosperm cells in the mature seed. The periphery of the endosperm is pressed against the thin seed coat (testa), consisting of cutinized and lignified dead cells The embryo is surrounded by three to five layers of rather thick-walled endosperm cells in the mature seed. The periphery of the endosperm is pressed against the thin seed coat (testa), consisting of cutinized and lignified dead cells Bud xs 10x

Reproductive Structures EMBRYO Cotyledons Radicle http://www.leubner.ch/anatomy.html# Endosperm Testa (seed coat)

Secretory Structures & Nicotine Tobacco leaves have 2 types of Trichomes Short stalked Nicotine Organic alkaloid and powerful neurotoxin Biosynthesis in roots, accumulate in leaves Long stalked Diterpeniods Talk about new potent tobacco plants that can produce more nicotine by shutting diterpenoid secretion to allow for more nicotine biosynthesis. Glover 2000

References Crang, R & Vassilyev A. Plant Anatomy CD. 2003. http://www.botany.org/ajb/00029122_di001557.html http://images.botany.org/set-14/ http://www.leubner.ch/anatomy.html# www.tobacco.org www.plantoftheweek.org http://www.landlfinecigars.com http://www.research.att.com http://www.botgard.ucla.edu Glover, Beverley J. Differentiation in plant epidermal cells. Journal of Experimental Botany. Vol. 51, No. 344, pg 497-505, March 2000.