Lesson II: The Wood Flashcards
- the hard fibrous material that forms the main substance of the trunk or branches of a tree or shrub, used for fuel or timber
WOOD
- the hard fibrous substance consisting basically of xylem that makes up the greater part of the stems, branches, and roots of trees or shrubs beneath the bark and is found to a limited extent in herbaceous plants
WOOD
The Plant Kingdom
Divided into:
(1) Thallophytes
(2) Bryophytes
(3) Pteridophytes
(4) Spermatophytes
- simplest plants; mostly unicellular; reproduce through cell division; includes bacteria, algae and fungi
Thallophytes
- represented by mosses and liverworts. This group has chlorophyll but structure is of primitive type.
Bryophytes
- stems, roots and leaves possess vascular tissues but are small and short-lived, although many are considered perennials. Reproduction involves spore formation.
Pteridophytes
- the seed-producing plants
Spermatophytes
Spermatophytes consists
of two major groups:
A.Gymnosperms
B.Angiosperms
- cone-bearing; seeds are naked and leaves are mostly needle-like or acicular if not subulate
Gymnosperms
Four (recognised) orders of Gymnosperms:
1) Cycadales
2) Gingkoales
3) Gnetales
4) Coniferales
- woody plants in the tropics resembling tree ferns and palms; e.g., oliva and pitogo
Cycadales
- monotype, restricted to a single species Gingko biloba of China and Japan
Gingkoales
- regarded as the most recent Order of the Gymnosperms in the phylogenetic sequence.
Gnetales
There are three families
under Order Gnetales:
(a) Family Welwitschiaceae
(b) Family Ephedraceae
(c) Family Gnetaceae
- monotype consisting of one genus
and species, Welwitschia mirabilis.
Family Welwitschiaceae
- single genus, Ephedra spp., a source of an alkaloid called “ephedrine” which is used as a substitute for adrenaline.
Family Ephedraceae
- single genus, Gnetum, with 30 species of small trees and woody lianas found in tropical forests.
Family Gnetaceae
- the only Order of the Gymnosperms capable of producing timber in commercial scale
Coniferales
- flowering plants; seed enclosed in an ovary and
most are broad-leaved
ANGIOSPERMS
ANGIOSPERMS divided into two:
i) monocots
ii) dicots
- with single seed leaf and scattered vascular bundles;
e.g., coconut
monocots
- two seed leaves with vascular tissues arranged in a ring form and also characterized by the presence of pith at the center of stem;
e.g., maple trees , olive trees, etc.
dicots
TWO DISTINCT ORGAN SYSTEMS IN PLANTS:
- Shoot System
- Root System
- the vegetative (non-reproductive) parts of the plant, such as the leaves and the stems; and the reproductive parts of the plant, which include flowers and fruits
Shoot System
- supports the plants and absorbs water and minerals
Root System
THE THREE BASIC TISSUE PATTERNS FOUND IN ROOTS AND STEMS:
- Dermal tissue
- Ground tissue
- Vascular bundles
– covers and protects; controls gas exchange and water absorption
- covered by a waxy cuticle
that prevents evaporative
water loss
Dermal tissue
Dermal tissue consists of:
a. Stomata
b. Root hairs
- specialized pores that allow gas exchange through holes in the cuticle
Stomata
- extensions of root epidermal cells, increase the surface area of the root, greatly contributing to the absorption of water and minerals.
Root hairs
- carries out different functions based on the cell type and location in the plant
Ground tissue
GROUND TISSUE IN DICOTS:
- Parenchyma
- Collenchyma
- Sclerenchyma
- photosynthesis in the leaves, and storage in the roots
Parenchyma
- shoot support in areas of active growth
Collenchyma
- shoot support in areas where growth has ceased
Sclerenchyma
- strand of primary tissues found within the stem of a plant and consisting of xylem and phloem, along with cambium
Vascular bundles
Wood is the _________ it is primarily because it is abundant, renewable, and usable from bark to treetop for everything from homes and buildings to paper and energy production
(NAFO, 2022).
ultimate renewable resource
Gross Internal Structure of Stem/Wood:
a. Bark
b. Cambium
c. Cork cambium (phellogen)
d. Wood/xylem
e. Pith
– outer part of the stem
Bark
– found between the bark and the wood, a layer of meristematic cell responsible for the increase in diameter of the stem
Cambium
– outer part of the bark that produces cork cells
Cork cambium (phellogen)
– inner part of the stem
Wood/xylem
– parenchymatous tissue inside
the xylem
Pith
Main physical properties of wood
include:
color,
luster,
texture,
macro-structure,
odor, moisture,
shrinkage,
internal stresses,
swelling,
cracking,
warping,
density,
sound –
electro – thermal conductivity
Determine the appearance of wood:
Сolor,
shine,
texture and
macrostructure
Gross Physical Features of Wood:
A. Texture
B. Color
C. Luster
D. Hardness
E. Weight
F. Odor
G. Taste
H. Grain direction
- refers to the size and proportional number of woody elements. Description of _____ in relation to the size of wood pores
Texture
- due to the presence of extractives
deposited in the wood cells. - may be used to distinguish some wood
Color
- the ability to reflect light.
Luster
- resistance to indentation. This may be known by cutting the sample with a knife or by applying
pressure with the fingernails on
the longitudinal surface of the
wood.
Hardness
- the weight of wood is
dependent on three factors:
(1) amount of wood substances
(2) moisture content
(3) amount of extractives present
some wood species give off distinct ____ which are efficient in distinguishing them from other specimens.
odors
most Philippine wood species are _____ but few species have distinct tastes like pagatpat which
tastes salty and batino which
has a bitter taste
tasteless
- this refers to the arrangement/orientation of the wood elements with respect to respect to the longitudinal axis
Grain direction
