Download Lecture 6 (Word doc)

Where we’ve been:
Basal Families:
•
Family: Amborellaceae
•
Family: Nymphaceae
Subclass Magnoliidae:
– Order Magnoliales
• Family: Magnoliaceae
– Order Laurales
• Family: Lauraceae
EUDICOTS:
‘Basal Tricolpates’:
– Order Ranunculales
• Family: Ranunculaceae
• Family: Berberidaceae
• Family: Papaveraceae
– Order Proteales
• Family: Platanaceae
How should we think about all of this information???
First, let’s think in terms of evolution:
Magnoliaceae as a baseline: primitive characteristics
• usually woody, and lacking vessels
• flower parts not well differentiated (corolla/calyx not distinct,
anthers/filaments not distinct)
• flower parts many!! (lots of spirally arranged tepals, stamens, carpels)
• flower parts free, not fused (tepals free, carpels free, stamens not adnate to
petals or connate)
• flowers PERFECT
• ovaries hypogynous, and carpels not sealed by fusion
• flowers radial, not bilateral
• leaves simple, entire and alternate – and often with aromatic oils
• monocolpate pollen
As we encounter new families, we will watch new ‘derived characters’ come on the scene. For
example:
Leaves can become:
• compound to twice- compound to…
• emarginate (toothed, lobed, etc.)
• opposite
Flowers can become:
• bilateral
• imperfect
Flower parts can:
• fuse, becoming connate or adnate
• differentiate
• reduce in number
• become more elegant/sophisticated in arrangement
Or, flower parts can modify in all kinds of interesting ways! Stay tuned……..
Next, let’s focus on characteristics of each family:
What are the basic traits?
– Overall habit
– Leaves
– Flowers:
• Perianth: calyx and corolla
• Androecium
• Gynoecium
– Fruit
– What is the norm for this family? What are the outliers like?
– What are some of the unique features that make this family distinctive?
Subclass: Caryophyllidae
Orders: Caryophyllales and Polygonales
• Primarily herbaceous and succulent
• Carpels usually 2 or more, connate
• Embryo usually curved
• Seed with perisperm rather than endosperm (perisperm is derived from nucellus, rather
than megasporangium; if you want to know more about this, we can talk in office hours;
I’m not concerned with your knowing this last tidbit)
• Color from betalains (except for Caryophyllaceae and Polygonaceae, where color is from
anthocyanins)
Caryophylales
•
•
18 families, 8600 species
We will focus on five of these families:
– Caryophyllaceae
– Amaranthaceae
– Aizoaceae
– Portulacaceae
– Cactaceae
Caryophyllaceae: The ‘Pink’ Family
Habit: Annual or perennial herbs.
Leaves: Opposite, simple, entire, often narrow. Pinnate
venation, but appearing parallel. Swollen nodes at points of leaf
attachment to stem.
Flowers: Radial, usually perfect.
- Perianth: Of calyx and “corolla” (corolla is actually made
up of petaloid staminodes). Calyx sometimes fused,
sometimes sepals with membranous margins. Sepals
persistent*. “petals” usually 5, often bilobed or ‘pinked’
(with zig-zagged apical margin, like carnation flowers).
Sometimes with claw-and-limb morphology (see photos
below). Petals usually pink, white or red.
*note that ‘sepals persistent’ means that the sepals do not fall
off of the flower even after the ovary has developed into fruit.
Notice this in the photos of capsules below.
- Androecium: Usually of 5-10 stamens. Filaments distinct
to connate to basally adnate to petals.
- Gynoecium: One pistil, 2-5 carpellate; styles 2-5, stigmas
2-5. Ovary superior.
Fruit: Usually a capsule, opening by valves or teeth.
Outliers: Reduced or absent ‘petals’. Flower parts in 4.
Gestalt: Swollen nodes; narrow, entire, simple leaves with
venation appearing parallel; ‘petals’ notched, pinked or with
claw-and-limb and corona (appendage at joint); sepals fused or
with membranous edge; perianth and Androecium parts 5 or 10.
Carpels opening by valves/teeth, with persistent sepals attached.
Notice:
•
•
•
•
Swollen nodes
Opposite leaves
Secondary venation subtle
Primary veins appear parallel
Cymose inflorescence with determinate flowering pattern; think here about what ‘determinate’
vs. ‘indeterminate’ means: with determinate flowering, the apical bud (which was the first to
develop) opens first. With indeterminate flowering, there is less of a pattern to the order of buds
opening.
Focus here (above photo) on the claw-and-limb structure of the petals; these petals are jointed,
and have an appendage at the joint; this appendage is called a corona. This petal structure is very
visible on the Silene that is on display in the lab/greenhouse.
Also notice above the gynophore, or androgynophore. This is a special stalk that supports the
ovaries and stamens in some members of this family. This is a structure that appears in some,
but not many, other families – we will encounter it again, but know that it is also a feature that
can be distinctive for this family.
Focus on same stuff as above: clawed petals with corona, and gynophore.
Notice the capsules opening by teeth, and also the persistent (and connate) sepals.
Agrostemma capsules:
I’ve included these images mostly to demonstrate again what a capsule opening by teeth would
look like, and to highlight what free central placentation looks like. Notice that seeds (and at one
point, ovules) were attached to a central column rather than to the sides of the locule, or to septa
that divide up the locule.
Curved Embryos:
Another new character that we encounter first in the Caryophyllales is a curvature of embryos.
In Caryophyllaceae, endosperm is replaced by perisperm; this is something that we will not
really get into in class (yet), and I don’t expect you to be able to tell me what perisperm is as
compared with endosperm. Just know that it is a nutritive source that supports the embryo
during development.
Seeds! Notice textured seed coat and curved embryos of Caryophyllaceae:
Amaranthaceae (incl. Chenopodaceae): ‘Amaranth
Family’
Habit: Usually herbs or somewhat shrubby. Often reddish
stems. Sometimes succulent.
Leaves: Alternate or opposite, simple, entire or undulate,
sometimes serrated or lobed. Sometimes succulent.
Mealy/scurfy leaves*.
* Mealy/scurfy refers to a thin powdery/scaly coating on the
leaves, that is sometimes visible with the naked eye, and
sometimes only with a microscope or hand-lens. Try looking at
the surface of some of these leaves under the scope, and
scratching at them with a pin to really see what this mealyscurfy business is referring to. It’ll make sense after you see it Flowers: Often tiny and densely packed. Usually bisexual, but
sometimes unisexual.
- Perianth: 3-5 tepals, green and herbaceous or fleshy to
white, pink or reddish, dry and papery.
- Androecium: 3-5 stamens opposite the tepals.
- Gynoecium: One pistil, 2-3 carpellate. Stigmas 1-3.
Ovary usually superior.
Fruit: Varied (most often an achene, utricle or circumcissile
capsule).
Outliers: Shrubs.
Gestalt: Tiny, densely packed flowers. Mealy scurfy leaves.
Often in disturbed, arid or saline places.
One typical ‘habit’:
Diverse inflorescence structure and overall morphology:
Can be succulent too:
Aizoaceae: ‘Stone Plant Family’
Habit: Succulent herbs.
Leaves: Usually opposite, simple, usually entire and succulent.
Veins +/- obscure. Leaf surface with large, bladder-like cells.
Flowers: Bisexual, radial, with hypanthium.
- Perianth: Usually 5 sepaloid tepals (but see Androecium).
- Androecium: Stamens 5-numerous, outer whorl(s) often
petal-like staminodes.
- Gynoecium: 2-5 connate carpels, ovary superior to
inferior.
Fruit: Usually capsule, sometimes fleshy, seeds sometimes
arillate.
Outliers:
Gestalt: Succulent plants, often prostrate, often with quite
showy flowers (ice plant)
Other cool stuff: Coastal/arid habitats. CAM.
Varied vegetation – similar flowers:
Similar vegetation – different flowers! (be careful):
Bladder-like cells – not always easy to see, but sometimes…
Portulacaceae: ‘Purslane Family’
Habit: Herbs or shrubs, succulent.
Leaves: Opposite or alternate, simple, entire, pinnate venation
but veins obscure (due to succulence).
Flowers: Bisexual, radial; 2 bracts subtending each flower that
appear to be sepals.
- Perianth: [2 sepal-like bracts, +] 4-6 tepals. Occasionally
tepals numerous, petal-like, distinct to slightly connate.
- Androecium: Usually 4-6, opposite tepals. Filaments
distinct or slightly adnate to tepals.
- Gynoecium: Usually 2-3 connate carpels. Ovary superior
or inferior.
Fruit: Usually a capsule, seeds sometimes arillate.
Outliers: Shrubs, more fleshy, appering almost like Aizoaceae
or Crassulaceae; Imperfect flowers.
Gestalt: Somewhat fleshy, succulent leaves; two sepal-like
bracts, usually 5 petal-like tepals.
Other cool things:: Pollen grains tricolpate to polycolpate to
polyporate. Sometimes CAM. Sometimes clonal (vegetative)
reproduction by bulbils (tiny little plantlets that fall off and root
independently; notice this on the Kalanchoe (Crassulaceae) on
display for week 4.
Lots of variation – leaf shape, flower size, flower color -
One basic form: notice sepal-like bracts subtending flower –
Cactaceae and Polygonaceae were covered in lecture on 4/19/05,
and I’ll not be annotating all of what we covered on that day.
Please rely on your notes, or if you were not present borrow
from a friend –
Cactaceae: ‘Cactus Family’
Primitive cacti have broad leaves!!
However, most cacti are ‘stem-succulents’ – with leaves modified to form spines, and without
broad leaves:
Areoles with spines:
Inflorescence of solitary flowers emerging from areole:
Ovary usually +/- inferior:
Fruit are berries, sometimes with stem tissue enclosing them:
Polygonaceae: ‘Knotweed Family’
Eriogonum sp.
OCREA: Stipules sheathing stem (not present in Eriogonum, but characteristic of this family for
other genera)
Notice angular ‘knotted’ habit of stems: