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Unit A: Continuity of Life
Chapter 1:
Classification of Living Things
Lesson 2 – Part 2:
How are Plants Classified?
II. Classifying Plants
E. Angiosperms
1. These are vascular plants.
2. Angiosperms, like gymnosperms, make seeds.
a. Seeds, in angiosperms, are produced in their flowers.
b. Eventually, those seeds are encased in a fruit.
1) The fruit is the part of the plant that contains the fertilized seeds.
2) Fruits are incredibly, almost maddenly, varied in their characteristics and appearance.
3) Fruits can be broadly divided into various categories, but can straddle several at once:
Fleshy Fruits vs Dry Fruits
Simple Fruits vs Aggregate Fruits vs Multiple Fruits
True Berries vs Modified Berries vs Accessory Fruits
a) Fleshy fruits are often edible and are seen in the fresh fruit and vegetable section
of the super market.
b) Dry fruits are all manner of things you probably didn’t even know were considered
a fruit at all.
1) Further, dry fruits can be divided into two more categories:
Dehiscent & Indehiscent
a) Dehiscent (“duh-HISS-ent”) means the (dry) fruit will eventually crack open
along two seams and shed their seeds into the environment when the fruit
is ripe.
b) Indehiscent (“in-duh-HISS-ent”) fruits retain their seeds and do not crack
open after ripening (almost all fleshy fruits are indehiscent).
2) Many important staple food crops, including grains, are actually dry fruits.
c) Simple fruits are fruits that have formed from a single ovary.
d) Aggregate fruits are formed from many ovaries from a single flower growing
together to form the fruit you pick and eat.
e) Multiple fruits are from many ovaries from multiple flowers (on one plant) growing
together to form the fruit you pick and eat.
f) Accessory fruits have the fleshy part formed not from the ovary (or not entirely
from the ovary), but from some other part(s) of the plant.
4) Also, there are compound ovaries, which can still form simple fruits!
5) So, for instance, you could have a simple fruit that is dry and indehiscent (dandelion),
or an aggregate, fleshy fruit which is considered accessory (strawberry).
Name: ___________________________________________________________________________________________
6) Examples of various fruits and their types include:
Fleshy Fruits
a) tomatoes, grapes, dates, peppers,
avacados, bananas, eggplants
(true berries – fruits come from a single ovary with
multiple seeds)
b) oranges, lemons,
limes, grapefruit
(hesperidiums - segmented berries;
the citrus fruit)
c) pumpkins, squash,
watermelons, cucumbers
(pepos - berries with hard rinds; the gourds)
d) apples & pears
(pomes; accessory fruit – fleshy part is formed from
something other than the ovary)
e) pineapples, figs, mulberries
(multiple fruit - many ovaries derived from many
individual flowers grow together; accessory fruit)
f) peaches, cherries, apricots
plums, olives, mangoes, coffee “beans”
(drupes (also called stonefruits) – having large, hard
pits (woody endocarps) around seed; accessory fruit)
Dry Fruits
j) green beans, peas, peanuts
(legumes – formed from a simple ovary and splits
open (dehisces) along 2 lines; also called a pod)
k) cotton bolls, poppies, primroses
(capsules – compound ovary forms a dry fruit that is
usually dehiscent)
l) acorns, chestnuts, hazelnuts
(nuts - indehiscent)
m) dandelion “fluff” or sunflower “seeds”
(achenes – simple, small, dry, single-seeded, & usually
having a thin fruit body attached to the seed at only
one point; indehiscent)
n) rice, corn, wheat
(grains - indehiscent)
o) walnuts, almonds, pistachios,
pecans, coconuts
(“drupe-like nuts” or “fibrous drupes” - indehiscent)
p) samara (from elms, ashes, & maples)
(winged seeds - indehiscent)
g) blackberries, raspberries
(aggregate fruit - many ovaries derived from a single
flower (of drupes (actually, druplets)—not berries!))
h) blueberries, cranberries, cactus
(false (epigynous) berries; accessory fruits)
i) strawberries
(accessory, aggregate fruit
(aggregates of indehiscent achenes!))
7) Not all fruits are edible.
8) In some cases, people don’t eat the fruit but do eat the seeds (cereals
like corn, legumes like black beans, and various nuts).
9) Some fruits are used to make other products altogether (like textiles
from cotton).
Name: ___________________________________________________________________________________________
3. Angiosperms produce pollen, like gymnosperms.
a. Pollen is necessary for the creation of seeds.
b. Pollen must unite with an egg in order for a seed to be created.
c. Pollen is produced in the flowers.
1) Sometimes, the male (pollen-producing) part of the plant, called the
androecium, is found as part of the same flower where the female (egg
producing) part of the plant, called the gynoecium, is found—this is called a
perfect flower.
2) Sometimes, there are male flowers (pollen producing), called staminate
flowers, and female (egg producing) flowers, called carpellate flowers.
a) These could be found on the same plant; this is called being monoecious.
b) These could be found on separate “male” and “female” versions of the
plant; this is called being dioecious.
c) Note, only the “female” version of the plant could actually produce fruit.
d) Dioecious species are rare, perhaps only 6% of angiosperms are dioecious.
d. The pollen contains the genetic information that must be mated with the
egg in order to produce an embryonic seed (the beginning a new plant).
1) Pollen must be moved from the male part of the flower to the female
part of the flower—or from the male flower to the female flower (which could
be on an entirely different plant), depending on how the plant is designed—in
a process called pollination.
2) Once the pollen reaches the female part of the plant, it must be joined
with the egg that is there in a process called fertilization.
e. Many angiosperms rely on insects like bees to pollinate themselves.
1) The flowers are of specific colorations (some in the ultraviolet wavelenths),
scents, and also may create nectar in order to attract the bees.
2) The bees come into the flower in order to get the nectar, incidentally get
pollen on themselves, then rub it off on other parts of the flower or on
another flower and pollinate the plants.
3) Bees are not the only animals that can aid in pollination; other animals include:
a) birds
b) bats
c) wasps
f. Some angiosperms, like grasses, produce no special attractants and rely instead
entirely on wind for pollination.
Name: ___________________________________________________________________________________________
A Typical “Perfect” Flower
https://www.boundless.com/biology/textbooks/boundless-biology-textbook/seed-plants-26/angiosperms-160/angiosperm-flowers-624-11845/
3) The stigma, style, and ovary form the pistol; pollen from the anthers
must be collected in the stigma, move down the style and into the ovary
to unite with the egg(s) found there.
a) The fertilized egg is the new plant embryo.
b) The ovary around the egg will form some kind of fruit body.
c) The fruit will:
1) Protect the seed.
2) Possibly aid in the dispersal of the seed.
3) Provide nourishment for the seed as it starts to grow.
Name: ___________________________________________________________________________________________
4. Angiosperms can be broadly divided into two categories according to particular
seed traits and a loose set of likely secondary characteristics often associated
with those seed traits; those two categories are:
Monocots & Dicots
a. The seeds of angiosperms may have one or two structures within that
resemble tiny leaves called cotyledons (kot-a-lee-dins).
b. Single cotyledon seeds are called monocots and have these distinguishing
features:
1)
2)
3)
4)
5)
Pollen has a single furrow or pore
Flower parts come in multiples of three
Major leaf veins run parallel
Stem’s vacular bundles are scattered
Roots develop adventitiously from stem nodes
(not from a single source like the radicle)
6) Secondary growth is absent, meaning these plants do not grow rings of
wood and bark
c. Two-cotyledon seeds are called dicots and have these distinguishing
features:
1)
2)
3)
4)
5)
6)
Pollen has three furrows or pores
Flower parts come in multiples of four or five
Major leaf veins are reticulated, not just running parallel
Stem’s vascular bundles form in a ring
Roots develop from the embryonic radicle throughout life of plant
Secondary growth is present, meaning these plants form wooden trunks
with bark
Name: ___________________________________________________________________________________________
F. Plant Adaptations
1. An adaptation is a physical or behavioral trait that helps an organism survive in
its habitat.
2. Examples of physical (or structural) traits in plants might include:
a. being deciduous (so leaves don’t freeze in winter)
b. having a waxy coating (to minimize water loss)
c. certain plants have life cycles of varying lengths:
1) annuals usually complete their life cycle in a single year
2) biennials live for two years
3) perennials grow back each spring for many successive years
3. Note that animals can also exhibit behavioral adaptive traits, which might
include:
a. birds flying south for the winter
b. certain animals hibernate through the winter months
c. some animals will always create a certain type of home (nest, burrow, dam,
etc.)
4. Note, adaptations do not arise as a result of exposure to a new environment,
nor are they caused by the climate or other such features of the environment;
creatures do not respond to changes in their environment with new
adaptations.
a. Adaptations are random variations present in the population of a certain life
form that turn out to be beneficial or of use in a certain environment that the
creature happens to find itself living in.
b. A feature that was not helpful in the past and becomes useful because of a
change in the environment then becomes an adaptation.
Name: ___________________________________________________________________________________________
G. A note about vegetables and other plant parts we eat:
1. Vegetables are parts of a plant that are edible that are not a fruit, specifically
the:
a. stems
 asparagus
 bamboo shoots
 bok choy
 broccoli
 celery
 rhubarb
b. roots
 beets
 onions
 carrots
 parsnips
 potatoes





radishes
rutabagas
sweet potatoes
yams
turnips
c. leaves
 Brussels sprouts
 parsley
 cabbages
 spinach
 collards
 turnip greens






kale
chard
lettuce
endives
mustard greens
watercress
2. However, things like broccoli and cauliflower are not fruits, either.
a. They are the flower of the plant, but that flower was never fertilized.
b. So, when you eat these, you’re just eating a flower.
Material above modified from material found at: http://science.jburroughs.org/resources/flower/fruit3.html, http://www.resnet.wm.edu/~mcmath/bio205/fruits.html,
http://waynesword.palomar.edu/fruitid1.htm, http://www.seriouseats.com/2010/04/what-are-the-differences-between-nuts-and-drupes.html,
http://theseedsite.co.uk/fruits.html, http://www.cactus-art.biz/note-book/Dictionary/Dictionary_E/dictionary_epigynous_berry.htm,
http://www.newworldencyclopedia.org/entry/Blueberry, http://www.eplantscience.com/index/fruit.php, http://www.northernontarioflora.ca/fruits_term_types.cfm,
http://www.ucmp.berkeley.edu/glossary/gloss8/monocotdicot.html,
https://books.google.com/books?id=wpDqAgAAQBAJ&pg=PA393&lpg=PA393&dq=false+berry+vs.+accessory+fruit&source=bl&ots=2K1FHZdBA1&sig=0U3GkoNM52kswGmJipxkAsg5UXw&hl=en&sa=X&
ved=0CGAQ6AEwDmoVChMIu-Ts3J7eyAIVxHI-Ch1F4QrY#v=onepage&q=false%20berry%20vs.%20accessory%20fruit&f=false, http://sciencelearn.org.nz/Contexts/Pollination/Science-Ideas-andConcepts/Attracting-pollinators, http://www.sciencealert.com/here-s-why-corn-is-a-fruit-capsicums-are-berries-rhubarb-s-a-vegetable-and,
Renner, S.S. & Ricklefs, R.E. (1995). "Dioecy and its correlates in the flowering plants". American Journal of Botany 82: 596–606