Transcript Inflorescences, Fruits and Seeds

Inflorescences,
Fruits and Seeds
So many, many terms…
So little time…
Inflorescence
 An inflorescence can be defined as the
shoot system which serves for the
formation of flowers and which is
modified accordingly.
 The inflorescence form and position is
important in routine identification as well
as in the determination of phylogenetic
relationships.
Inflorescence Types
 Two quite different inflorescence types
occur in angiosperms. These are:
 Determinate (monotelic) inflorescences
 Indeterminate (polytelic) inflorescences
Determinate Inflorescence
 The main axis of the inflorescence ends
in a flower.
 The flowering sequence of a determinate
inflorescence usually begins with the
terminal flower at the top of the cluster.
 Determinate inflorescences are generally
ancestral to indeterminate ones.
Indeterminate
Florescence
 The growing point produces only lateral
flowers or partial inflorescences (groups
of flowers).
 The flowering sequence usually starts at
the base (or outside) of the cluster.
Diagramatic
Representation
Determinate
Inflorescenses
 The circles represent flowers and their
sequence of opening (from large to small).
Determinate
Inflorescences
 Cymes are one of the most common
types of determinate inflorescences.
 The lateral branches of cymes are
composed of usually numerous, threeflowered units usually showing opposite
branching.
Types of Cymes
Some Common Kinds of
Indeterminate
Inflorescences
 The circles indicate flowers; their size indicates
the sequence of opening (from large to small).
Racemes and Spikes
Indeterminate Inflorescence
 A raceme is an inflorescence with a
single axis bearing flowers with pedicels.
 A spike is similar to a raceme but the
flowers are sessile (lacking a pedicel or
stalk).
Raceme Example
Spike Example
Corymbs and Panicles
Indeterminate Inflorescence
 A corymb is a raceme with the pedicels of
the lowermost flowers elongated,
bringing all of the flowers to the
approximate same level
 A panicle is merely a compound raceme,
that has two or more orders of branches,
with each axis bearing flowers or higherorder axes.
Corymb Example
Panicle Example
Head or capitulum
 A head (or capitulum) is a dense terminal
cluster of sessile flowers.
 In a determinate head, the central flowers
open first.
 In an indeterminate head, the peripheral
(outermost) flowers open first.
Helianthus annuus
Umbel
 An umbel is an inflorescence in which all of the
flowers often have pedicels of approximately
equal length that arise from a single region at
the apex of the inflorescence axis.
 Umbels are determinate if the flowers open
from the center first and then proceed to the
periphery.
 Umbels are indeterminate if the flowers open
from the periphery first and then proceed to the
center.
Umbel Example
Umbel Example II
More on inflorescences
 Simple inflorescences have only a single
axis (one order of branching).
 Compound inflorescences have two or
more orders of branching.
Catkin or Ament
 Any elongated
inflorescence
composed of
numerous
inconspicuous,
usually wind
pollinated flowers.
Willows have catkins.
Epiphyllous Flowers
 Some flowers are borne on leaves.
Cauliflorous Flowers
 Some flowers are borne on older stems or
trunks.
Tendrils
 Inflorescences are sometimes modified for
climbing by becoming elongated and twining or
developing adhesive pads, thus forming
tendrils.
Fruit
 A fruit is a matured ovary along with fused
accessory structures (hypanthium or perianth
parts).
 There is great diversity of size, form, texture,
means of opening, and anatomy among fruits.
 Many structures that a botanist considers to be
fruits are neither sweet nor good to eat!
 Seed dispersal is the primary function of fruits.
Parts of the Fruit
Pericarp
aka ovary wall
 In some fruits, the pericarp becomes very
juicy as it matures. Often, such a fruit
has a high sugar content and is readily
consumed by animals.
 The pericarp in many other plants dries
as it matures.
Pericarp
 Often, the pericarp is dehiscent, splitting
open and releasing the seeds that it
contains.
 In other plants, the fruit is indehiscent;
the seeds remain enclosed within
pericarp tissue.
Pericarp
 The pericarp is often differentiated into layers,
particularly in fleshy fruits.
 The exocarp is the outer skinlike layer.
 The mesocarp is the middle layer that often
becomes soft and fleshy.
 Only certain kinds of fruit have a third layer, the
endocarp. This innermost layer closely
surrounds the seed or seeds. (ie hard pit of
olive or papery apple core).
 A tomato is a fleshy fruit that does not have
endocarp.
Simple Fruits
 Simple fruits result from a single flower.
 Simple fruits are divided into 2
categories.
 1) Those formed from a single carpel or
several fused carpels.
 2) Those formed from several separate
carpels of a single gynoecium (aggregate
fruits).
Common Types of Simple
Fruit
 Fruit fleshy at maturity:
 Berry – entire pericarp soft; generally
with two or more seeds. Derived from
either superior or inferior ovaries.
Examples: tomato, banana, and grape.
Includes the pome, the pepo, and the
hesperidium.
Fruit Types associated
with Berries
 Pome – Derived from an inferior ovary and surrounded
by a fleshy hypanthium. Restricted to the Rosaceae
subfamily Maloideae. Examples: pear, apple, and
quince.
 Pepo – Derived from an inferior ovary with a leathery
rind. Generally restricted to Cucurbiaceae family
(watermelon, pumpkin, cucumber).
 Hesperidium – Derived from a superior ovary with a
leather pericarp having oil glands. The carpels are
easily separated as segments that are lined with fleshy
hairs. Restricted to Citrus and its close relatives
(Rutaceae). Oranges, lemons, grapefruit.
Common Types of Simple
Fruit
 Fruits fleshy at maturity.
 Drupe – Pericarp distinguishable as
three layers: exocarp, mesocarp, and
endocarp. The endocarp is a ‘stone’ that
encloses the seed. Examples: peach,
plum, cherry, coconut, olive.
Common Types of Simple
Fruit
 Fruit dry, one-seeded, not breaking apart
at maturity.
 Achene – Extremely variable in form.
Seed and pericarp attached only by the
funiculus (ovule stalk). Examples:
buttercup, buckwheat. Includes also
samara, cysella, and utricle.
 Samara – A winged achene. Examples
are elm, ash, and birch.
 Cypsella – An achene with adnate calyx
(pappus) Examples: members of the
Asteraceae family such as the dandelion.
 Utricle – A bladdery achene with the wall
loosely surrounding the seed. Example:
pigweed.
Common Types of Simple
Fruit
 Fruit dry, one-seeded, not breaking apart
at maturity.
 Caryopsis – Seed coat and pericarp
completely adnate. Restricted to
Poaceae family. Examples: maize,
wheat, rye, barely, sorghum.

Common Types of Simple
Fruit
 Fruit dry, one-seeded, not breaking apart
at maturity.
 Nut - Exocarp hard; the fruit often
subtended by an involucre (whorl of
bracts). Derived from a syncarpous
synoecium, but one-seeded by abortion
of ovules. Examples: acorn, filbert.
Common Types of Simple
Fruit
 Fruit fleshy or dry, at maturity breaking into
one- or a few-seeded segments, the seeds
remain completely surrounded by the pericarp.
 Schizocarp – Fruit breaking into onecarpellate segments (mericarps). Examples:
members of the Apiaceae such as fennel and
dill, and others such as hollyhock. Schizocarps
may be winged (samaroid schizocarps) as in
maple or fleshy as in madder.
Common Types of Simple
Fruit
 Fruit fleshy or dry, at maturity breaking
into one- or a few-seeded segments, the
seeds remain completely surrounded by
the pericarp.
 Nutlet – Friut deeply four-lobed, breaking
into one-seeded half-carpellate
segments; used especially for fruits of
borage, vervain, and mint families.
Examples: sage, borage.
Common Types of Simple
Fruit
 Fruit dry at maturity dehiscing either
lengthwise, or by pores, teeth or a lid and
exposing the seeds.
 Capsule – Syncarpous and typically
several- to many-seeded. Perhaps the
most common and certainly the most
variable of dehiscent fruits.
 Septicidal capsule – Opens lengthwise
along the septa. Example: zigadene.
 Loculicidal capsule – Opens lengthwise
between the septa and directly into the
locule (evening primrose and iris).
 Poricidal capsule – Opens by pores
near the top (poppy)
 Schizocarpic capsule – Breaks
completely apart at the septa into oneseeded segments (castor bean).
 Denticidal capsule – Opens apically by
a ring of teeth (Eucalyptus, chickweed)
 Circumscissile capsule – Opens
horizontally in a ring so that a lid is
formed (purslane, plantain, portulaca)
Common Types of Simple
Fruit
 Fruit dry at maturity dehiscing either
lengthwise, or by pores, teeth or a lid and
exposing the seeds.
 Silique – A long, narrow (more than twice
as long as broad) 2-carpellate fruit whose
outer walls break away from a central
papery partition. Restricted to
Brassicaceae. Examples mustard, kale.
Silique
Common Types of Simple
Fruit
 Fruit dry at maturity dehiscing either
lengthwise, or by pores, teeth or a lid and
exposing the seeds.
 Follicle – Unicarpellate, dehiscing along
one suture (Examples: milkweed,
larkspur).
Milkweed Follicle
Common Types of Simple
Fruit
 Fruit dry at maturity dehiscing either
lengthwise, or by pores, teeth or a lid and
exposing the seeds.
 Legume – Unicarpellate, dehiscing along
two sutures. Restricted to the Fabaceae.
Examples: Bean and pea.
Simple Fruit Derived from
more than one ovary.
 Fruit derived from a flower with an
apocarpous gynoecium.
 Aggregate – The ovary of each carpel
matures into one of the simple fruits
described previously. A raspberry is an
aggregate of small drupes.
Simple Fruit Derived from
more than one ovary.
 Fruit derived from a flower with an
apocarpous gynoecium.
 Accessory – Tissue other than or in
addition to the ovary enlarges and
becomes fleshy. Examples: strawberry
and blackberry in which the receptacle
becomes fleshy.
Simple Fruit Derived from
more than one ovary.
 Fruit derived from a flower with an
apocarpous gynoecium.
 Hip – The hypanthium of a perigynous
flower enlarges and becomes fleshy at
maturity but does not become adherent
to the carpels. Known only from certain
Rosaceae, especially Rosa. The ovaries
usually mature into achenes.
Simple Fruit Derived from
more than one ovary.
 Fruit derived from a flower with an
apocarpous gynoecium.
Multiple Fruit
 A multiple fruit is the product of the gynoecia of several
closely clustered flowers.
 The individual ovaries of each flower develop into one
of the simple fruits described previously. Accessory
tissue such as the calyx of the mulberry or the
inflorescence axis of the pineapple may become fleshy.
The fruit appears to be ‘merged’ together.
 The synconium is a special kind of multiple fruit
restricted to Ficus (fig) where the inflorescence axis
enlarges and surrounds the flowers and becomes
fleshy. The individual ovaries mature as achenes.
Seed
 A seed is a matured ovule that contains
an embryo and often its nutritive tissues
(endosperm, perisperm).
 The seed is surrounded by a seed coat.
 Seeds may be variously sized and
shaped. They may be associated with a
wing or tuft of hairs.
Endosperm
 Endosperm is a usually triploid tissue derived
from the union of the two nuclei in the central
cell of the female gametophyte. Endosperm
may be homogeneous (uniform in texture) or
ruminate (dissected by partitions that grow
inward from the seed coat).
 Endosperm may contain starch, oils, proteins,
oligosaccharides, and/or hemicellulose.
 Endosperm may be hard to soft and fleshy.
Perisperm
 Perisperm is a specialized diploid
nutritive tissue derived from the
megasporangium.
Seed Coat
 The testa (plural testae) of a seed coat
develops from the outer integument.
 The tegmen (plural tegmina) of a seed coat
develops from the inner integument.
 The testa varies in surface texture due to the
pattern and outgrowths of the individual cells
composing its surface.
 The testa is sometimes colorful and fleshy.
More on Seeds
 Some seeds are associated with a hard
to soft, oily to fleshy, and often brightly
colored structre called an aril.
 An aril is usually an outgrowth of the
funiculus or the outer integument.
 The seed bears a scar called the hilum
(plural hila) at the point where it was
attached to the funiculus.
Seed Embryo
 The embryo consists of an epicotyl, a
radicle, a hypocotyl, and usually one or
two cotyledons (seedling leaves).
Seed Embryos Continued
 The epicotyl develops into the shoot.
 The radicle develops into the primary root
and usually gives rise to the root system.
 The hypocotyl connects the epicotyl and
radicle.
 The cotyledons (seedling leaves) may be
leaflike, fleshy, or modified as nutrientabsorptive structures.