Sesbania herbacea Arrives in the Falls Lake Area

Sesbanias are tall, scrawny weeds in the pea and bean family, the Fabaceae.  Their shape and compound leaves are said to resemble a young Mimosa sapling or a Wild Senna.  Sesbania vesicaria (Bagpod) has become common in the Falls Lake region, but Sesbania herbacea is a relatively new arrival.  Sesbania herbacea has colorful common names like Danglepod, Coffeeweed, and Colorado River Hemp.  It is a native annual with a spotty distribution in North Carolina, occurring and sometimes colonizing areas where it has been accidentally introduced.  It can even hang on as far north as Massachusetts, far from its normal home in the southern coastal plain.  From a distance, its form appears insubstantial, melting into the green of background plants, as illustrated by the following photo.

Sesbania herbacea Coffeeweed

Sesbania herbacea
Coffeeweed

The stem is round and smooth, with a distinct gray bloom.  A bloom is a waxy or powdery coating on the surface of a stem that can easily be wiped away by the touch of a finger.  The bloom is especially noticeable on S. herbacea.

Sesbania herbacea Coffeeweed Stem with Bloom

Sesbania herbacea
Coffeeweed
Stem with Bloom

S. herbacea has alternate, compound leaves with large numbers of opposite leaflets.  The high number of leaflets give the leaves a feathery appearance.

Sesbania herbacea Coffeeweed Compound Leaves

Sesbania herbacea
Coffeeweed
Compound Leaves

A closer look at a leaf blade reveals, below, that the opposite leaflets on this plant often become alternate as the leaf develops.

Sesbania herbacea Coffeeweed Opposite (?) Leaflets

Sesbania herbacea
Coffeeweed
Opposite (?) Leaflets

The outer surface of the petals of the unopened flowers are a rich, red color.  Flower color varies greatly among Sesbanias, and is not a reliable indicator of species.  The flowers of this particular plant consistently did not begin to open until 1:00 pm, and were not fully open until 3:00 pm.

Sesbania herbacea Coffeeweed Unopened Petals

Sesbania herbacea
Coffeeweed
Unopened Petals

The orange upper 3/4ths of the flower is called the banner.   The yellow inner part of the banner petals are influenced by the outer red, making the petals appear orange.  The pure yellow petals drooping  straight down are called the wings.  In the second photo below, the reddish structure called the keel can be seen between the two yellow wings.  The keel petals enfold the pistil and stamens.  These flower structures are typical of members of the bean family, Fabaceae.

Sesbania herbacea Coffeeweed Open Flower

Sesbania herbacea
Coffeeweed
Open Flower

Sesbania herbacea Coffeeweed Flowers

Sesbania herbacea
Coffeeweed
Flowers

Long, sickle-like fruits or pods begin to extend from the flowers that have finished their bloom.  These sickle-like pods are the easiest way to distinguish Sesbania herbacea from its close relative Sesbania vesicaria.

Sesbania herbacea Coffeeweed Developing Pods

Sesbania herbacea
Coffeeweed
Developing Pods

Below is an isolated  view of the young,  developing pods.

Sesbania herbacea Coffeeweed Pods

Sesbania herbacea
Coffeeweed
Pods

The pods of Sesbania vesicaria (Bagpod) are completely different from those illustrated above.  Bagpods, as the name implies, have short, compact pods that contain only 2 large seeds each.  See below.

Close-Up of Outer and Inner Layers of Pod Sesbania vesicaria

Close-Up of Outer and Inner Layers of Pod
Sesbania vesicaria

To compare the flowers and fruits of these two close relatives, check out this link to an article on Sesbania vesicaria.

https://bwwellsassociation.wordpress.com/2013/12/20/sesbania-vesicaria-bagpod-at-falls-lake-north-Carolina/

Herb Amyx

 

 

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