9/27/2014 4:56 AM
Boechera pendulocarpa, Hoboell’s rockcress, drop-seed
rockcress; Brassicaceae family
Some sources still call it Arabis Hoboellii. Southwest Colorado Wildflowers doesn’t have B.
pendulocarpa but they detail the evolution of name changes for the Boechera genus
and say that the species are difficult to tell apart.
It is native.
It is not a favorite plant so, of course, I don’t have a lot
of photographs.
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The branches and leaves are very different. The flowers are
similar. Can it be the same species? Probably not.
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B. pendulocarpa is biennial or short term perennial from ‘a
crown’. Jepson Herbarium uses the word ‘caudex’ rather than the word ‘crown’.
They say a stem rises from each caudex branch. E-FLORA BC
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B. pendulocarpa has a rosette of basal leaves.
This photo shows the ‘persistent’ caudex extending between
the rosette and the root. It looks rather woody, here. Some source said the
caudex of B. pendulocarpa was not woody. [A caudex is a perennating organ, the
organ that allows a perennial plant to persist from growing season to growing
season.]
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B. perdulocarpa has many alternate cauline leaves.
It appears in this photo that the horizontal basal leaves
evolve into vertical cauline leaves.
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A cauline leaf with branched hairs [trichomes].
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The inflorescence is a raceme so, of course, the leading bud
falls to the side as it is succeeded by another leading bud that is reaching
for the sky.
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The flowers continue to mature as the plant grows higher so
those at the bottom of the inflorescence may be in fruit while those at the top
of the plant are still in bud.
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4 petals white or pink, 4 sepals, sepals hairy, 6 stamen, no
style. If it has no style then the stigma must be seated directly on the ovary.
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The split structure in the photo below is a bit of a
mystery. But it must be stamen, 3 on the near side of the stigma, 3 on the far
side.
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The fruit are beginning to emerge from the ovaries or,
perhaps the ovaries are elongating. The greenish tips with a bit of flair would
seem to be a bit of style with its stigma. Yes, a source did say there was no
style.
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There are several names for dry fruits. The fruit, here, is
a silique. It is made up of two carpels. It is dehiscent, it opens on maturity.
The brown was the ovary, that is, the covering for the ovum, but now we change
its name and call it … in this case, two valves that open, on maturity. The
partition … Yeah, there’s a lot of stuff to remember. The pistil was, in this
case, made up of two carpels. The pistil has become a fruit, a silique … made
up of two carpels. There are seeds in each carpel. The outside of the carpel
[now called a valve] peels away exposing the seeds that were attached to the …
oops … I don’t know where they were attached. But the opening valves have
exposed the ‘replum’, a persistent partition. The ‘partition’ is, of course,
the other side of the carpel, the side where the two carpels are joined.
Not enough to remember? Ok, siliques and silicles are the
same thing but the length of siliques is over three times its width. The length
of silicles is less than three times its width.
I see this ‘formula’ related to seeds in a couple of sources,
2n=14. I wonder if that means there are 2 carpels with14 seeds in each carpel.
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The petals, sepals and stamen have fallen away from the
brown fruit farther down the stem. But, once again, it looks like there is a
vestigial style and stigma on the fruit.
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The leading buds are out of focus, but there, it seems, they
are. They look different. I wonder if they are ‘the end of the line’ and will
not develop.
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The nice brown fruit are green, here.
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The smooth green and brown fruit are hairy, here.
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It really interests me how good the plants look in your photos.
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