PLANT ORGAN – LEAVES
TOBACCO (Nicotiana tabacum)
• Christopher Columbus and other early European explorers discovered the native
peoples of North and South America growing tobacco, drying, curing the leaves and
then smoking, chewing or snuffing them.
• It was used for medicinal purposes as well as for religious rituals. Shamans in the
Amazon, fasted and smoked large quantities of tobacco to produce hallucinations,
which they interpreted as visits from spirits.
• Many Europeans had adopted the habit of smoking, its popularity enhanced by
tobacco’s supposed medicinal values. It was touted as a cure for everything from
headaches to snakebites and was also used as an aphrodisiac.
• The physiologically active ingredients are nicotine and related alkaloids, which are
colorless, bitter chemicals that affect the CNS.
• When inhaled, nicotine, which is habit forming, is absorbed through the lung
membranes and produces a stimulating sensation.
• Pure nicotine, however, is poisonous absorbed in large amounts, it produces nauseas,
dizziness and hallucinations.
Leaf Form and Structure
• Leaves may be round, needlelike, scalelike, cylindrical, heart shaped, fan shaped or
thin and narrow.
• Most leaves are composed of two parts, a blade and a petiole.
• They vary in size from those of the raffia palm (Raphia ruffia), whose leaves often
grow to more than 20 meters (65ft) long, to those of water-meal (Wolffia), whose
leaves are so small that 16 of them laid end to end measure 2.5 cms (1inch).
• Axil - Angle between the upper side of
a leaf and the stem from which it
grows. Knowing the location of the axil
helps you to locate the bud.
• Stipule - Leaflike outgrowths usually
present in pairs at the base of the
petiole.
• Petiole - The stalk that attaches the
blade to the stem.
• Vein - The vascular tissue of the leaf
and are located in the spongy layer of
the mesophyll
• Blade - Broad, flat portion of a leaf.
*Sessile leaf lacks a petiole and has a blade directly attached to the stem, often by a sheath
that encircles the stem.
PHBIOSC201 – Pharm. Botany w/ Taxonomy Lecture
Rody Rica B. Agdipa, RPh
, White Ash (Fraxinus americana) – pinnately compound, leaflets are borne
on a axis that is a continuation of the petiole.
Ohio buckeye (Aesculus glabra) – palmately compound, leaflets arise
from a common point at the end of the petiole.
California white oak (Quercus lobata) – simple leaf (single blade).
Sugar maple (Acer saccharum) – opposite leaf arrangement, two leaves
grow at each node.
Southern catalpa (Catalpa bignonioides) – whorled leaf arrangement,
three or more leaves grow at each node.
American beech(Fagus grandifolia) – alternate leaf arrangement, which
one leaf at each node.
PHBIOSC201 – Pharm. Botany w/ Taxonomy Lecture
Rody Rica B. Agdipa, RPh
TOBACCO (Nicotiana tabacum)
• Christopher Columbus and other early European explorers discovered the native
peoples of North and South America growing tobacco, drying, curing the leaves and
then smoking, chewing or snuffing them.
• It was used for medicinal purposes as well as for religious rituals. Shamans in the
Amazon, fasted and smoked large quantities of tobacco to produce hallucinations,
which they interpreted as visits from spirits.
• Many Europeans had adopted the habit of smoking, its popularity enhanced by
tobacco’s supposed medicinal values. It was touted as a cure for everything from
headaches to snakebites and was also used as an aphrodisiac.
• The physiologically active ingredients are nicotine and related alkaloids, which are
colorless, bitter chemicals that affect the CNS.
• When inhaled, nicotine, which is habit forming, is absorbed through the lung
membranes and produces a stimulating sensation.
• Pure nicotine, however, is poisonous absorbed in large amounts, it produces nauseas,
dizziness and hallucinations.
Leaf Form and Structure
• Leaves may be round, needlelike, scalelike, cylindrical, heart shaped, fan shaped or
thin and narrow.
• Most leaves are composed of two parts, a blade and a petiole.
• They vary in size from those of the raffia palm (Raphia ruffia), whose leaves often
grow to more than 20 meters (65ft) long, to those of water-meal (Wolffia), whose
leaves are so small that 16 of them laid end to end measure 2.5 cms (1inch).
• Axil - Angle between the upper side of
a leaf and the stem from which it
grows. Knowing the location of the axil
helps you to locate the bud.
• Stipule - Leaflike outgrowths usually
present in pairs at the base of the
petiole.
• Petiole - The stalk that attaches the
blade to the stem.
• Vein - The vascular tissue of the leaf
and are located in the spongy layer of
the mesophyll
• Blade - Broad, flat portion of a leaf.
*Sessile leaf lacks a petiole and has a blade directly attached to the stem, often by a sheath
that encircles the stem.
PHBIOSC201 – Pharm. Botany w/ Taxonomy Lecture
Rody Rica B. Agdipa, RPh
, White Ash (Fraxinus americana) – pinnately compound, leaflets are borne
on a axis that is a continuation of the petiole.
Ohio buckeye (Aesculus glabra) – palmately compound, leaflets arise
from a common point at the end of the petiole.
California white oak (Quercus lobata) – simple leaf (single blade).
Sugar maple (Acer saccharum) – opposite leaf arrangement, two leaves
grow at each node.
Southern catalpa (Catalpa bignonioides) – whorled leaf arrangement,
three or more leaves grow at each node.
American beech(Fagus grandifolia) – alternate leaf arrangement, which
one leaf at each node.
PHBIOSC201 – Pharm. Botany w/ Taxonomy Lecture
Rody Rica B. Agdipa, RPh
