Biological Sciences Department
Index Herbariourm

A Comprehensive Guide to Physalis Fuzz

If you will be using a key to identify Physalis species, resign yourself to looking at the vegetative hairs, as they provide some of the most clear cut traits for species identification. Physalis plants are hairy little organisms, and even those that apparently lack hairs often have a few if you look close enough.

Where to look: You'll need to know how the hairs on the plant are oriented (up, out, or down) and the easiest place to see this is on the stalks leading to the fruit or flower. Stems and petioles also work.

Hair Orientations
Antrorse: paralleling the stem and pointing up toward the tip of the plant. A common type -- most plants have at least a few.
Divergent: pointing out every which way from the stem. This type of hair orientation is also widespread.
Retrorse: paralleling the stem and pointing down toward the base of the plant. An unusual orientation.
Notes on Hair Orientations

When it comes to hair orientations, we generally take the majority rule approach. If lots point forward, they're antrorse, and if lots point backward, they're retrorse. Since most species can also have some divergent hairs mixed in, having a few of those in the mix doesn't change that. Only if the plant has an overwhelming majority of divergent hairs do we place it in the divergent-haired category.
Hair Types
Simple: unbranched hairs usually 1/2 to 3 mm long. Some may be gland tipped (central hair above), giving the plant a sticky feel if numerous.
Pretend you don't see these: most species that are supposed to have only unbranched hairs also have the occasional slightly branched hair. Just ignore them.
Branched: sometimes called stellate, but more Y-branched than star-shaped. Often short (under 1mm) and dense, giving the plant a velvety look.

Missing Hair Types among Kentucky Physalis

As of yet, none of the "stellate" haired species of Physalis (like the widespread P. cinerascens) have been reported from Kentucky.

Characteristics of Kentucky Species

P. alkekengi: glabrous to sparsely hairy with simple, non-glandular hairs.
P. angulata
:
very nearly hairless. A few short, simple antrorse hairs if you look hard.
P. grisea: densely fuzzy with simple, 0.5 mm or longer non-glandular hairs. (Glands may be present, but are on hairs shorter than 0.5 mm). Orientation is divergent.
P. heterophylla
:
fuzzy, with dense hairs from 1/2 mm to about 3 mm. They are divergent, simple, and may or may not be glandular. It's the clammy ground-cherry because they usually are, giving the leaves a sticky (like glue) feel.
P. longifolia:
sparsely hairy. The flower stalks and calyces have short, simple, antrorse hairs.
P. philadelphica:
sparsely hairy with simple, non-glandular hairs.
P. pubescens:
Aptly named. Densely fuzzy with long, simple, often glandular hairs. Orientation is divergent.
P. virginiana
:
falls somewhere between sparsely hairy and fuzzy. The hairs are simple, non-glandular, and have a retrorse orientation.

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