Plant Species of the Borrego Desert: Campanulaceae: Nemacladus twisselmannii, Twisselmann's nemacladus

Fig. 1. Two plants of Nemacladus twisselmannii, Twisselmann's nemacladus, amidst typical small sand grains, showing two color variations of the plants. All flowers are in fruit except for the single flower in the picture on the right with the white petals. The flowers and fruit are typically 3 mm in length; these entire plants are just 6 mm (~1/4 inch) tall. The plant we vouchered was among the largest plants, at 13 mm tall and 24 mm wide (1/2 in tall and 1 inch wide). Click on photos for larger versions.
Photos by Keir Morse; see also additional photos from Keir.


Table of Contents

Introduction

Origin and Meaning of Name
Distinguishing Characteristics and Similar Species
Pictures of Young Plants, Mature Plants, and Dead Plants
Habitat, Distribution and Abundance
References


Introduction

On 28 April 2012, as part of a floristic survey of the Wilson Trail area at Pinyon Ridge near 4000 feet elevation by all the authors, the first author was exploring a small sandy wash to look for Nemacladus and other similar diminitive plants. N. longiflorus var. breviflorus was found and recognized immediately, but there was a much smaller plant next to it that did not look like anything we had ever seen before (See picture with caption given below).

Examination with a hand lens revealed what looked like a Nemacladus flower, but we had no idea which species it was. In the field, we scanned the illustrations in the Jepson Manual. The plants strongly resembled the illustration of N. twisselmannii, but we summarily rejected that determination, since N. twisselmannii is an extremely rare plant known only from a single small area in the southernmost Sierra Nevada 210 miles away, at a much higher elevation of 7350 feet.

At home that night, we were absolutely flabbergasted when we compared our pictures to Nemacladus Pictures by Nancy Morin, and our plants were a perfect match to N. twisselmannii.

This is just about as implausible a find and determination as one could ever imagine.

N. twisselmannii is among the rarest plant species in California. There are only two known populations, from an area of less than ten total acres, in northernmost Kern County north of Lake Isabella (Isabella Lake on the USGS topographic map), containing a total of about 400 plants. They grow in a completely different habitat, an open mostly barren area on a steep rocky slope with a deep cover of decomposed granite and granitic sand in the pine forest, than the flat sandy wash in the desert transition habitat here. The description of the habitat is from the type voucher and topotype voucher.

Yet we could find no other determination, and Nancy Morin immediately kindly confirmed the determination. Nancy commented:

For me the defining characteristics include the really big ovary that seems to be in fruit almost before the flowers have had a chance to do much, the hairs all over the plant (nothing else in Nemacladus has hairs like this), and of course the very compact plant. N. t. shares with N. californicus the rosette producing an axillary stem making another rosette, which is almost never seen in N. t. because the plants rarely get big enough to create another stem. It is fascinating that these axillary stems in your plants have such long internodes, too. The calyx lobes look to be shorter in your plants than in the Pine Flat location.

We cannot even imagine how this species could be found in two such different localities separated by 210 miles, unless there are overlooked populations elsewhere. It would be extremely easy to overlook populations of this species, so it is difficult to say that there are not populations elsewhere.

We spent 30 minutes looking for enough plants (20) so that we could voucher one. Pictures of that vouchered plant are below. The plant we vouchered was among the largest plants around, at 13 mm tall and 24 mm wide (1/2 in tall and 1 inch wide), and had fruit and flowers.

We plan to conduct further surveys here to try to locate additional populations.

Origin and Meaning of Name

Distinguishing Characteristics and Similar Species

Pictures of Habitat,Young Plants, Mature Plants, and Dead Plants

Click on pictures to get larger versions

The photos below are all by Tom Chester and Kate Harper. See also 17 additional photos of these and other plants nearby from Keir Morse.

Habitat

The plants have so far only been found in this small section of a flattish open sandy wash around 2 m (6 feet) wide. Keir Morse is studying one of the first plants found, in an area that had about ten plants. The foreground area, with a pink ribbon in it, contains a few additional plants. For these, and all pictures shown below, click on the picture to get a larger version.
These pictures show additional views of the same wash as above.

Young Plant Pictures

Mature Plant Pictures

Size comparison to Nemacladus longiflorus var. breviflorus (the larger plant on right). The N. twisselmannii (Plant 1 in the numbering scheme used here) is the almost completely-invisible gray smudge just touching the pen in the lower left of the picture. An unusually-colored Lasthenia gracilis is on the left side of the picture, and a small Erodium cicutarium in fruit at upper right. The pen is 13.5 cm long.

Plant 2.
The color difference between rows 1 and 2, and rows 3 and 4, is due to the use of a flash in rows 3 and 4.

Plant 3

Plant 4

Plant 5

Plant 6

Plant Group 7 (Two Plants)

Plant Group 8 (Two Plants)
The color difference between rows 1 and 2 is due to the use of a flash in row 2.

Vouchered Plant

Voucher after two days of pressing:

Click on pictures to get larger versions

Dead Plant Pictures

Habitat, Distribution and Abundance

References


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Copyright © 2012 by Kate Harper, Tom Chester, Keir Morse, RT Hawke and Shaun Hawke.
Commercial rights reserved. Permission is granted to reproduce any or all of this page for individual or non-profit institutional internal use as long as credit is given to us at this source:
http://tchester.org/bd/species/campanulaceae/nemacladus_twisselmannii.html
Comments and feedback: Kate Harper
Updated 5 May 2012.