10/3/2014 7:38 AM
10/9/2014 2:39 AM
Microseris nutans vs Agoseris glauca
These plants are impossible to do much with, confined to my
existing photos. They, too, await more photos next year. I’ll do what I can
with what I have.
Are the plants Microseris nutans or Agoseris glauca, both,
or something else? They are from different genus but they look a lot alike. This
may be an example of convergent evolution. [Convergent evolution: Organisms not
closely related independently evolve similar traits as a result of having to
adapt to similar environments or ecological niches.]
Though Burke says M. nutans is a bit earlier, the flowering
period of the two plants mostly overlaps. They are present in flower at the
same time.
The flower-heads of these plants look a lot like dandelions.
A few have a bit, not much, of a dandelion look in their leaves with their
pointed margins.
They are both Asteraceae family, as it the common dandelion,
and neither these plants nor dandelions have disk flowers. The flowerheads are all
ray flowers.
Reminder:
In the Asteraceae family what look to us like flowers are
not flowers but huge bunches of flowers in an inflorescence, a ‘flowerhead’. A
flowerhead is one of the many patterns of inflorescence.
The top of the stem thickens. It develops a receptacle. A
flower sits on the receptacle.
In Asteraceae family plants the receptacle grows quite broad
and more or less flat. A dozen or so to hundreds of flowers [florets] sit on
the receptacle. There are usually two kinds of flowers making up the Asteraceae
flowerheads, disk flowers and ray flowers. Disk flowres in the center and ray
flowers around the edge.
Sometimes there are only disk flowers and some times there
are only ray flowers. As I said above, these two species and the common
dandelion have only ray flowers.
The bracts around a single flower are sepals and as a group
they are the calyx. The bracts around the whole flowerhead are phyllaries and
as a group they are the involucre. The long green spikes we see when these
flowers are closed are the phyllaries of their involucre. The phyllaries
provide clues for distinguishing the two species.
These are both flowers that open in the morning and close in
mid-day heat. The green involucre phyllaries rise up and close, hiding the yellow
ray flowers.
*
Alibi time: As I’ve said before, I knew even less botany
when I took these images than I do now. The photos of these plants accumulated
over three years, maybe more. Even so, there are few photos to choose from. And
my work as a filing clerk was not adequate.
There are very few of these plants in Drumheller Springs
Park
Later, I probably assumed that, as M. nutans is a shade
earlier than A. glauca the plant I saw first, east of the north access path
near north pond was M. nutans and the plants I saw later near the horseshoe
stub of long rock ridge were A. glauca.
The park is 10 acres or so and I never walk the whole park.
Couldn’t if I wanted to. So who knows which plant blossomed first? I don’t. But
maybe next year … yeah, yeah.
Whatever.
Identification
At present I am comparing plant descriptions from Burke
Herbarium UW, Jepson Herbarium UC Berkeley, E-FLORA BC
This reading and these photos have me wondering if I am
looking at even more than two species.
The sources say of both species that they are highly
variable, and so it seems.
The two flower heads look much the same. Some sources say
the span of the number of rays for A. glauca can be twice that of M. nutans, up
to 75 for M. nutans, up to 150 for A. glauca so it seems that A. glauca can be
much larger. None of my photos show as few as 15 ray flowers. I doubt if any
show 150 ray flowers.
Some unidentified flower heads
The following photos are obviously in various stages of
development.
010
015
020
030
035
The cupped ligules of the ray flowers in the photo below suggest to me that the flowerhead is in the act of closing.
040
The flower-stalk, the peduncle, on A. glauca is always said
to be a scape, a leafless stalk rising from the ground with a single flower at
the top of the stalk.
The flower-stalk on M. nutans is almost always said to be
branched but Burke says, “… the stem simple and curved to robust, branching and
erect …”. I don’t know if Burke is saying it can have a scape.
A. glauca is always said to have basal leaves, only. The
basal leaves are highly variable. But photos in Burke, E-Flora BC
M. nutans is said to have both basal and cauline leaves. The
leaves are said to be long and narrow. I don’t have photos showing branched
stems and basal leaves. Basal leaves may be obscured by grasses in some photos.
The two photos below are Agoseris glauca. The stems are
scapes, they have only basal leaves but the basal leaves are long and narrow
like those of Microseris nutans.
050
060
The photo below is Microseris nutans. The plant has long
narrow cauline leaves [leaves on the stem]. If there were basal leaves they
were not preserved. The flower-stalk is branched. The buds of M. nutans are
said to be ‘nodding’. The bud here is rising to erect position. The leaves are
low on the plant. The flower-stalk above the leaves has a bit of the scape
look.
070
And here we have a plant past flowering that branches at the
base, seems to have scape like flower-stalks and rather broad basal leaves.
Darn.
080
And here is a plant with several branching stems. It has no
apparent basal leaves. It has long narrow cauline leaves low on the plant. It
must be M. nutans.
090 – June 19, 2011
Some diverse leaves of Microseris nutans
100 – DSC01439, May 04, 2012
110 – DSC01441 -
120 – DSC02143, May 19, 2012
130 – June 03, 2011
140 – May 24, 2012 – DSC0246- and DSC0247- photos all from
this day.
I spent a lot of time Googling vocabulary.
The botanists descriptions of the shape of the involucre is
no help at all with making sense of my photographs. They say the involucres are
cylindric, bell shaped, fusiform, [spindle shaped] ovoid [egg shaped], obconic
to hemispheric [a special case of cone shape to a shape that is half a sphere]
This is what I have derived from their descriptions of the
phyllaries [Reminder: phyllaries are involucre bracts.]:
If the outer phyllaries are shorter and the inner phyllaries
have dark hair then M. nutans.
If the inner and outer phyllaries are about equal in length
and the surface of the phyllaries have black spots or stripes then A. glauca.
If there is white hair then A. glauca. If the outer series of phyllaries are
overlapped [imbricate] then A. glauca.
Microseris Glauca
The dark hairs on the inner series of phyllaries are
distinct in the photo below. The shorter outer series of phyllaries is a little
less distinct.
150
160
170
The black hairs and the short outer phyllaries are less
distinct.
180
The short outer phyllaries are distinct here. But there
isn’t a black hair on the inner phyllaries and the outer phyllaries are covered
with white hairs. White hairs should indicate Agoseris glauca. A lot of the
pappus is in sharp focus and it does not have the plumose pappus of Microseris
nutans.
190
And here we have black hairs and short outer phyllaries of
M. nutans and the reddish markings of A. glauca.
195
Agoseris glauca
Some portraits of critters so cousin Pat won’t be too bored.
The phyllaries are overlapped. The phyllaries are distinctly white-hairy. The
overlapping phyllaries indicate Agoseris glauca on the photo below.
200
This photo has the white hairs and phyllaries of equal
length. It doesn’t look to me like the phyllaries are overlapped. It looks like
there are three or more series of phyllaries.
210
The phyllaries of about the same length with black specks on
the phyllaries identify Agoseris nutans on the photos below.
220
There is a little overlapping of the phyllaries, here.
230
I supposed this was a husk or an inflorescence on a plant
that died but Jepson says the phyllaries of A. glauca can be ‘rosy-purple’.
240
Some diverse involucre shapes
250
260
270
Reminders:
Fruit: ‘a ripened ovary’. What was the ovary wall is now the
‘pericarp’, a thin covering over the seed. The seed was the ovum [the egg] before
it ripened.
An achene is a small, thin walled, one-seeded, dry,
indehiscent [It doesn’t open on maturity, it has to rot away.] fruit.
A cypsela is the fruit of the Asteraceae family. It is an
achene. The cypsela seems to be an achene that has an umbrella on top [a
pappus]. Think of the fruit in the blowball of the common dandelion.
The ray of the ‘umbrella’ are said to be modified sepals.
And they are also said to be scales. I can’t find a definition of scale that
makes sense in this context. I’ve checked several botanical dictionaries.
*
The modified sepals of the cypsela of M. nutans are
‘plumose’ … they have a feathery appearance. Those of A. glauca do not.
Microseris nutans
280
290
300
305
310
Agoseris glauca
320
330
340
I must have been faking dissection. I assume these fruits
would elongate if left to ripen.
Oops. Looks like some strangers slipped in. These have
‘stems’ like those on dandelion fruit. None of the fruit in photos of what I
believe to be M. nutans or A. glauca have stems. These have distinctive stems.
Oh, well. More observations to pay attention to next year, if there is a next
year.
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