Ribes velutinum in flower Picture by Michael Charters Lightning Ridge, San Gabriel Mountains 18 June 2005 |
Ribes velutinum and R. lasianthum | 
Ribes velutinum in fruit Picture by Tom Chester Lightning Ridge, San Gabriel Mountains 13 July 2013 |
| Click on any of the pictures on this page to get larger versions. | ||
Introduction and Field Observations
Photographs From Lightning Ridge, San Gabriel Mountains
Analysis From Photographs
Conclusions
Photographs From Outside of Southern California
Introduction and Field Observations
Ribes velutinum and R. lasianthum have been problematic species in southern California. In particular, the plants at Lightning Ridge, in the Blue Ridge section of the San Gabriel Mountains 4.4 air miles west of Wrightwood, have confused us in the past, as well as people determining vouchers. One duplicate collection by Orlando Mistretta and R. T. Hawke, made on 29 June 1995, is determined as R. lasianthum at RSA, and as R. velutinum at UCR!
When Michael Charters botanized a section of the PCT here in July 2013, he sent a pix of one of the Lightning Ridge area plants to Tom Chester for determination. Looking at Michael's pix of the fruit, the fruit appeared to be that of R. velutinum, but the dried flower on it appeared to be that of R. lasianthum. This stimulated Tom to spend some time on 12 July 2013 analyzing online pictures of the two species and looking at online voucher records.
It quickly became clear that something was amiss here, and some serious field study was needed. In addition to the problem with different determinations of duplicate vouchers, analysis of voucher elevations of R. lasianthum in the Sierra Nevada indicated that one would not expect it this species to occur at Lightning Ridge, for the following reason.
In general, non-riparian montane species have a minimum elevation that increases to the south. This is expected since the climate is hotter and drier to the south, and hence such species have to go to higher elevation to have the same water availability. Riparian species always have available water, so in general don't need to retreat to higher elevations to the south.
See the Consortium of California Herbaria plot of latitude vs. elevation for R. montigenum, which is only found above 8000 feet in southern California except for a few vouchers with problems either in their determination or elevation. Its minimum elevation, ignoring the problem vouchers, fits the smooth trend of the minimum elevation increase to the south.
From the similar plot for R. lasianthum, it would also be expected that R. lasianthum would occur only above about 8000 feet elevation in southern California.
Since the elevation of Lightning Ridge is about 7400 feet, and other vouchers of "R. lasianthum" were as low as 6100 and 6600 feet in the San Gabriel Mountains, this looked like a southern California voucher determination problem for the vouchers below 8000 feet, with those vouchers not actually being of R. lasianthum.
In addition to wondering what species was actually present at Lightning Ridge, Tom was struck by how similar the spines were on Michael's plant to those of R. montigenum and was curious to study them in the field, too.
Hence the next day, 13 July 2013, Michael and Tom, joined by Walt Fidler, met at Lightning Ridge to study the plants there.
These two species are separated in Munz 1974 and the Jepson Manual Second Edition 2012 as follows:
Free part of fl.-tube ca. 4 mm long, longer than wide; berry glabrous, red .... R. lasianthum
Free part of fl.-tube 2-3 mm long, ± as long as wide; berry gen soft-pubescent or glandular, dark, yellow becoming purple .... R. velutinum
The free part of the flower tube is what is somewhat-confusingly given as the hypanthium length in the Jepson Manual, which is explicitly said to be only the part of the hypanthium above the part fused to the ovary, which is its free part. In the following, for brevity we'll follow that same convention.
The following photograph labels the different parts of the Ribes flower:
To Tom's great surprise, the very first plant we studied appeared to be a perfect R. lasianthum, with a single ~glabrous red fruit and a dried hypanthium that was 4 mm long and 1.0 to 1.5 mm wide, clearly longer than wide. We then went through the entire description of R. lasianthum from both the Jepson Manual Second Edition 2012 and from Munz 1974, and they seemed to fit this plant perfectly! (No flowers were present, so that part of the description could not be checked against this plant.)
We were thus quite convinced this plant was R. lasianthum, which is what both Jane Strong and Tom concluded from measuring flowers back in June 2003. This meant that Tom's expectation from the elevation plot was not shared by this species. But just as plants don't always read the floras and have the characteristics given in them, neither do they always follow Tom's theoretical expectations. (:-)
We then looked at a plant just 20 feet away or so. It was a perfect R. velutinum! It had berries that were yellowish-green when young, turning reddish and then brownish. Its hypanthia were shorter, as long as wide, 2 mm long and 1.5 mm wide.
We were amazed!! Both species were here, and side by side no less. This raised no suspicions for us, since just on the previous trip at San Jacinto Mountain we had found two other similar species, Chimaphila menziesii and Pyrola picta growing side by side, which Walt had wanted to study. We just thought we got lucky once again in finding two species side by side that we all wanted to study.
Now that we thought we knew what both species looked like, we began to survey the area and GPS the locations of plants of each species to make a geographic map of each species here.
We almost immediately found a patch of seven plants all in one spot, six of which were clear R. velutinum,with dark fruits and short hypanthia, and one of which appeared to be clear R. lasianthum, with red fruits with long hypanthia. Walt surveyed off-trail in this area and found more R. velutinum.
This seemed a bit suspicious, especially since we found there were plenty of red fruits on the R. velutinum that had not yet turned dark. So then we looked at the single plant of "R. lasianthum" here in more detail, and were puzzled, finding some dried hypanthia that were about as long as wide.
We then returned to the first plant that we called R. lasianthum, and found that it, too, had some shorter hypanthia that were as wide as long. Its determination was no longer so clear to us.
The answer quickly became clear as we surveyed more plants. We found a ton more plants on the Lightning Ridge Nature Trail, and then on the PCT westward.
All the plants were the same, and quite clearly R. velutinum. All had berries that first turned red, then grew darker. They all had the same range for the ratio of the hypanthium length to width, as well as the ratio of the sepal length to hypanthium length consistent only with the values for R. velutinum. The ratio of the hypanthium length to width increases from flowers to fruit, and is larger for red fruit than for green fruit. The habits of the plants were all similar: robust, with mostly upright stems, with a maximum height of close to 2 m.
It also was completely clear to us how some vouchers of these plants could only be determined as R. lasianthum, given the current floral descriptions and keys, even though all these plants are actually R. velutinum. This nicely explains the two different determinations of the voucher duplicates discussed above, and why we had originally thought in 2003 that the plants here were R. lasianthum.
The problem with current floral descriptions and keys, that lead to misdeterminations of plants of R. velutinum as R. lasianthum, are:
The pictures below document this variation.
These problems can be traced to the original paper that described R. velutinum, that described only one form of this widespread species, from a plant in northern California.
The southern California plants differ in many ways to the northern California plant in the type description. The floral descriptions of R. velutinum have expanded greatly through the years as plants from different parts of its range were collected and analyzed. But have missed including the above two characteristics so far. R. velutinum is found throughout the western United States, and the plants in the San Gabriel Mountains are probably the southwesternmost plants of its range. It would not be unexpected for any species to have somewhat different characteristics at the end of its range.
Photographs From Lightning Ridge, San Gabriel Mountains
Pictures of the fruit below are given roughly in order of the color progression from light green to dark green, to yellowish green, to reddish, to brownish. This is presumably the order of color change as the fruit ripens, but we don't know that for sure. We have assumed that the berries start out light green from the flower pix at the top of the page showing light green very young fruit. The light green berries below appear to be the smallest, supporting that assumption. Although no attempt was made to have the pictures all on the same scale, most of the pictures were taken in the same way in the field, with the berries all at about the same distance from the camera.
These photographs were taken by selecting the most-accessible berries without any regard for their color or the length of the dried flowers. The goal of most the photographs was to measure the hypanthium length to width ratio, so for most photographs the dried hypanthium is perpendicular to the camera lens. A few of the pictures below were crops from a picture taken at larger distances from the fruit, or pictures that were taken to show the bracts below the fruit, and hence those fruits may not be perpendicular to the camera lens. Those pictures were not used in the measurements analyzed in the next section.
Click on any of the pictures to get a larger version.
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Analysis From Photographs
In each of the larger-version photographs linked above of the fruit where the hypanthium was perpendicular to the lens, Tom measured the length and width of the hypanthium, and the length of the sepals. Since the scale is in general not given, everything was normalized by dividing by the length of the hypanthium, producing two measured quantities independent of the scale of the picture: the width / length of the hypanthium, and the sepal length / hypanthium length.
Photographs of flowers of R. lasianthum and R. velutinum from Calphotos and from Michael Charters were measured in the same way, including Michael's picture at the top of this page.
Note that it is not always abundantly clear where either the lower or upper end of the hypanthium is in photographs, nor are the flowers known to be exactly perpendular to the camera for the photographs not taken by us. Both of these will introduce additional scatter in our measurements.
There were only three photographs of R. lasianthum at Calphotos that could be measured reliably, two of flowers, from Sonora Pass and from Schenk Camp, and one of young fruit. The most reliable measurements came from the pix of young fruit, since it was hard to tell in the picture of flowers exactly where the bottom and top of the hypanthium were located.
Oddly, these are essentially the only online photographs of R. lasianthum that show the flowers or fruit from the side. For a widespread species with 114 vouchers, this seems surprising. But perhaps the high elevations at which this species is found accounts for the lack of pictures.
Fig. 1 shows the results:
Fig. 1. The hypanthium width / length ratio plotted versus the sepal length / hypanthium length ratio, for R. lasianthum and R. velutinum, measured from pictures. Measurements are separated by those from flowers and fruit (LR = Lightning Ridge). Measurements from green fruits of R. velutinum are noted by green diamonds behind the blue triangles for all fruit.
The most striking result shown in Fig. 1 is that the ratio of the hypanthium width to length decreases significantly from flower to fruit for both species. This may be due to the hypanthium shrinking in width by a greater percentage than it shrinks in length.
Fig. 1 also shows that although the ratio of the sepal length to the hypanthium length is quite variable, the ratio of the sepal length to hypanthium length for R. velutinum is smaller for red fruit than for green fruit. This may be due to a change with time, or it may have something to do with the first flowers to form versus later flowers.
The values for the sepal and hypanthium length for these two species in the Jepson Manual translate to a sepal / hypanthium ratio of 1.0 to 1.5 for R. velutinum, and less than 0.7 for R. lasianthum. Considering the additional error due to the measurements from photographs discussed above, these ranges are consistent with all the data in Fig. 1 except for the measurement from one photograph of the flowers of R. lasianthum from the Mojave National Preserve by Jim Andre. The measurement from that picture might be skewed high, since the flowers do not appear to be exactly perpendicular to the camera, which would make the measurement of the hypanthium length artificially low. Also, measurements on this photograph are probably not very accurate due to the small size of the flowers in the pix. We've included that point in the plot so that the reader can decide whether to toss that point or not.
The floras only give qualitative information on the hypanthium widths, so we do not have a reference value for the two species for that ratio of the hypanthium width to length. The floras just state that the ratio is ± 1 for R. velutinum, and smaller than 1 for R. lasianthum. The floras do not state whether that applies to the hypanthium in flower or in fruit, which clearly makes a big difference.
Fig. 1 shows that the flowers of R. velutinum do appear to have a hypanthium length comparable to its width, with the ratio of the width / length around unity. But it is not obvious that the flowers of R. lasianthum have a significantly-different ratio, just a slight shift to lower values for the few points of R. lasianthum compared to the corresponding points for R. velutinum. And the floras make no mention that this ratio changes in fruit. Thus this qualitative key seems not very helpful in distinguishing the species.
Conclusions
Photographs From Outside of Southern California
Paul Slichter's East of the Cascade Mountains of Oregon and Washington of the old variety gooddingii. This has the only fruit we know of that is yellow, and it appears to be an immature fruit.
Robert L. Carr's photographs from Eastern Washington and Adjacent Idaho.
Tom Chester's photographs from the Grand Canyon Bright Angel Trail, with a comparison to R. leptanthum.
This page has been significantly improved by discussion with Jane Strong, especially her insight that the ratio of the hypanthium length to width changes from green fruit to red fruit.