Plants of Southern California: Gnaphalium canescens subspecies
Gnaphalium is an interesting genus with a number of delightful mostly-distinctive species, all called everlastings in their common names. However, for reasons that are not completely clear to me, two subspecies of G. canescens, sspp. beneolens (fragrant everlasting) and microcephalum (white everlasting), often prove difficult to correctly identify, even though the subspecies are quite distinctive once you have seen them.
(There are two other subspecies of G. canescens not found at lower elevations in cismontane Southern California and hence not considered here. The ssp. thermale is found in Southern California only at elevations of mostly 5000-7000 feet in the SnGb, SnBr, and SnJt. It has heads 4-5 mm in length, compared to heads of 5-6 mm in length for the other subspecies. The ssp. canescens is found only in the DMtns.)
In fact, I was confused for years about beneolens, because Lathrop and Thorne had called all the specimens at the Santa Rosa Plateau microcephalum. In my pre-keying days, I could see that there were two distinct but similar taxa there, one green and one white, but since Lathrop and Thorne only had that single taxon there, in my novice days I wasn't going to argue with them about it.
Finally, James Dillane showed me the two different taxa at Daley Ranch, and this led me to realize that Lathrop and Thorne had not distinguished the two taxa.
In fact, the overwhelmingly-dominant taxon at the Santa Rosa Plateau Ecological Reserve is ssp. beneolens.
The following pictures will make the difference clear.
Both of these taxa are short-lived perennials, and can be found with leaves at any time of the year. The following picture was taken at the Santa Rosa Plateau Ecological Reserve on 11 June 2005:
The white plant at upper left is ssp. microcephalum, and the greenish plant at lower right is ssp. beneolens. (The seedling plant at lower left is Hirschfeldia incana, shortpod mustard.)
This picture was randomly taken as the first example I came across that showed both taxa in a single photograph. These plants are quite representative of the average specimen for each taxa in the leaf characteristics, but are not representative of an overall average specimen, which will have the remaining dead inflorescences from the previous year. These plants had been mowed to the ground during trail maintenance a few months earlier. It makes it easier to see the leaves without the dead inflorescences hanging around.
The mowing makes no difference in the appearance of these young shoots, which appear identically as young shoots in plants with dead inflorescences. For some very-odd reason, these young shoots are called "basal leaf tufts" in the JM key. This confused me for years as well until I realized they just meant young shoots! These young shoots are simply the stems that will produce next year's flowers, and are usually present, but short, at the time of flowering on what were the young shoots in the previous year.
The leaves of the two subspecies are shown next to each other in the following photograph, each viewed from above:
The difference is pretty striking, yes? The leaves of ssp. beneolens are greenish, mostly linear to very-narrowly oblanceolate, and have a tendency to be ascending (see first picture). The leaves of ssp. microcephalum are whitish, very woolly, wider, and are distinctly narrowly oblanceolate. Those leaves have a tendency to be spreading, but as you can see, some leaves are ascending as well.
Some 90% of the time, a simple glance at a specimen, at any stage of its life cycle, will immediately reveal the identification.
Unfortunately, 10% of the time, closer inspection is needed. Did you notice in the above pictures that some of the leaves of ssp. microcephalum also have a greenish cast? And that some of the leaves of ssp. beneolens have a whitish cast? That's one problem in viewing an isolated plant; sometimes it is hard to be sure on which side of the white/green line the leaves fall.
Worse, some specimens of each species can have leaves nearly the same color, making it impossible to use the color to separate the species. See the two pages by Michael Charters linked below for examples.
Another problem is that sometimes the leaves of ssp. beneolens are a tad bit more oblanceolate, and the leaves of ssp. microcephalum are a tad less oblanceolate. The shape of the leaves is usually a reliable discriminant, but again, sometimes it may be difficult to call a plant viewed in isolation.
Finally, although many plants show the characteristic difference between the ascending to appressed leaves for ssp. beneolens and spreading leaves for ssp. microcephalum, the above example shows that this characteristic is a bit tricky to rely on by itself.
With this variation in all three characteristics, sometimes one has to view a couple of nearly plants before it becomes clear what the identification is for a single specimen.
The key in the JM uses the leaf characteristics given above to separate the two taxa:10. Lvs narrowly lanceolate, cauline ascending to erect .... ssp. beneolens
10'. Lvs ± oblong to spoon-shaped, cauline spreading ... ssp. microcephalum
Note that for some curious reason, the JM key calls the shape of the leaf of ssp. beneolens "narrowly lanceolate" instead of "narrowly oblanceolate".
The key in Munz uses an entirely different characteristic to separate the two taxa, whether the leaf is decurrent or not, which means whether the leaf blade continues along the stem or simply ends where it is attached to the stem. The following picture, made from two pictures from Michael Charters taken from the links given below, shows the difference:
Note how the ssp. beneolens leaf in the top portion of the above picture travels quite some length down the stem before merging into the stem, and is therefore strongly decurrent. The leaf attachment to the stem is discernable almost halfway to the next leaf! In contrast, the leaf of ssp. microcephalum stops fairly abruptly at the stem; it is not decurrent or only weakly so. (Also note that color would be of no help in discriminating the two taxa in these pictures; they are both greenish-white.
A final odd thing has to do with the common name of fragrant everlasting for ssp. beneolens. Most people detect only a very slight fragrance for ssp. beneolens, and some people detect zero fragrance from it. The common name must come simply from the fact that there is a faint detectable scent for ssp. beneolens, whereas ssp. microcephalum has almost no detectable scent. A better common name would be just-barely-fragrant everlasting.
For more pictures of these two taxa, see the excellent pictures on these two pages of Michael's Charters: ssp. beneolens and ssp. microcephalum.
By the way, these subspecies have been treated in the past as the species G. beneolens and G. microcephalum (e.g., in Munz 1974), and apparently will be treated in the future Jepson Manual as the species Pseudognaphalium beneolens and P. microcephalum. One can make an argument either way, since they certainly are as distinct in morphology and geographic distribution as many other taxa accorded the species rank. But they do share enough similar properties that a plausible argument can be made that subspecies are taxonomically more appropriate. Overall, compared to the ~1800 taxa I've seen so far in Southern California, I would lean slightly toward putting these at the species level as being more appropriate, but I wouldn't quibble with either placement.
Other species sometimes confused with these two subspecies:
- Sometimes, ssp. microcephalum is confused with G. stramineum. The best way to distinguish the two is to note that G. stramineum is an annual, and will never have multiple shoots coming from the ground. G. stramineum can appear as a multiple-stem plant, but all the stems come from the base of the main stem.
The following picture shows G. stramineum:
Note the clear annual appearance for this specimen. An examination of the base of the plant will show it is loosely attached to the ground, with no woody portion to the stem at all.
The leaves are not always so green as they appear in the above picture, and they are indeed hairy above, despite the appearance in the above picture. (The picture was taken by flash, so the colors are not exactly as would be seen by the eye in daylight, but the color is close.) The distinction between "green" and "gray" in the JM key is one that trips many beginning keyers, since it is difficult to realize that the plant above has to key under the "gray" portion of the key. It is better to ignore the color portion of the JM key, and treat "green" as glabrous, and "gray" as hairy.
The habitat for G. stramineum is also different from ssp. microcephalum. G. stramineum typically grows in moist areas, such as seasonal drainages; ssp. microcephalum grows in open slopes and chaparral.
G. stramineum is clearly a confusing taxon to many people, since Munz says that it is the species most often brought into the Rancho Santa Ana Herbarium to get an identification. I speculate that is because it is only seen in abundance in wetter than normal years.
Seedlings of G. stramineum are very distinctive, with leaves that are oblong for most of their length, but then with an almost circular bulge at the tip.
- Sometimes, G. canescens ssp. beneolens is confused with G. leucocephalum. The easiest way to distinguish them is that the upper side of the leaf for ssp. beneolens is tomentose, whereas the leaf for G. leucocephalum is glandular-hairy above, not tomentose. The flower heads for G. leucocephalum are larger, 6.5-7 mm in length compared to the 5-6 mm heads of ssp. beneolens.
The habitat is also different. G. leucocephalum grows in dry, sandy creek bottoms below ~150 m (500 feet) elevation, whereas ssp. beneolens grows on open slopes to a much higher elevation of 1200 m (4000 feet).
Copyright © 2006 by Tom Chester
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Last update: 9 February 2006