Lemna Yungensis, a New Duckweed Species from Rocks of the Andean Yungas in Bolivia

Lemna yungensis, a new duckweed species from rocks of the Andean Yungas in Bolivia

Autor(en): Landolt, Elias

Objekttyp: Article

Zeitschrift: Bulletin of the Geobotanical Institute ETH

Band (Jahr): 64 (1998)

PDF erstellt am: 06.10.2021

Persistenter Link: http://doi.org/10.5169/seals-377813

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Ein Dienst der ETH-Bibliothek ETH Zürich, Rämistrasse 101, 8092 Zürich, Schweiz, www.library.ethz.ch

http://www.e-periodica.ch E. Landolt

Lemna yungensìs, a new duckweed species from rocks of the Andean Yungas in Bolivia Elias Landolt Geobotanisches Institut ETH, Zürichbergstrasse 38, 8044 Zürich, Switzerland; [email protected]

Summary Lemna yungensìs, a new species from the Yungas in Bolivia growing on perpendicular wet rocks is described. It belongs to the section Uninerves Hegelmaier and is related to L. valdiviana. Its geographical distribution seems to be very limited.

Keywords: Bolivia, duckweed, Lemnayungensis, rock plants, water plants, Yunga

Bulletin ofthe Geobotanica! Institute ETH(1998), 64, 15-21

Introduction

On a visit to Bolivia in 1991, I revised the Therefore, I went for a second trip to Bolivia Lemnaceae material in the Herbarium LPB, to look for the new Lemna. This time we La Paz. One specimen attracted my attention. walked along the road and were able to find It was a Lemna similar to L. valdiviana. However, the plant. In addition, we detected it at three the fronds were of rather large size, and other places in the same region. they grew in a region with very high precipitation where otherwise no members of the family Description of Lemna yungensis occur: Bolivia, Province of Nor-Yungas, Departamento of La Paz: 89.5 km NE, below Morphology and systematic Chuspipata (20.2 km S of Yolosa. 16°17' S, position 67°49' W; 2350 m a.s.l.; cloud forest, in Fronds 3-6 mm long and 1.5-4 mm wide, permanently wet places; J.C. Solomon 8101, 19 1.5-2 times as long as wide, ± symmetric, July 1982). three to few coherent in small groups, ovate On our way to the Beni lowland we passed to lanceolate, flat, without small papillae the place. However, the road crossing the along midline of adaxial surface; sometimes steep slope of the Andes was narrow and with a slightly reddish violet colour along the busy, and we could not stop at the right place. margins of the fronds; nerve 1 prominent, Dr. S. Beck, Herbario Nacional de Bolivia, running through at least 3/4 of the distance was so kind to send the herbarium specimen between node and apex, longer than extension later to our Institute for further investigation. of air spaces; largest air spaces shorter When I sent the voucher back to La Paz than 0.2 mm; turions absent. Root up to 2 together with duplicates of all Lemnaceae cm long; tip rounded or slightly pointed; which I collected in Bolivia, it was lost and sheath unwinged; flowers and fruits not with it the unicate voucher from the Yungas. known (Fig. lc).

Bulletin ofthe Geobotanical Institute ETH, 64, 15-21 15 Lemna yungensis, a new duckweed from Bolivia

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/%. 7. (aj Natural habitat (rock wall) of Lemna yungensis between Chuspipala and Yolosa, (b) street wall in La Paz with Lemna valdiviana, (c) cultivatedfronds (5x) of Lemna yungensis Nr. 9207, and (d) Lemna valdiviana Nr. 9222.

Bulletin ofthe Geobotanical Institute ETH, 64, 15-21 E. Landolt

The species belongs to section Uninerves temperatures are 15-20 °C according to the Hegelmaier and is most related to L. altitude. The temperature drops rarely below valdiviana Phil. (Fig. Id). It differs from this 10 °C, frost never occurs. species by its larger size and the more or less symmetric shape (in L. valdiviana fronds are Geographical distribution usually narrower than 2.5 mm and often The new species was found at the following distinctly asymmetric at the base of the frond), places which are all situated in the department by the absence of small papillae along the of La Paz (Fig. 2): midline (in L. valdiviana often present) and by 1. Main road between Chuspipata and the sometimes slightly reddish violet colour Yolosa, northnortheast of Sacramento, of the frond margin (in L. valdiviana no 2440 m a.s.l.; vertical rock northwest to reddish violet colour present). west exposed, steadily overflown by water; growing on the wet rock or within mosses. Habitat 19.7.1996. Landolt 1/96. ETH Nr. (of living Lemna yungensis grows on permanently wet Lemnaceae clones) 9207. Typus location! rocks between c. 1400 and 2500 m a.s.l. (Fig. 2. Same locality and similar habitat as in Nr. 1, la). The rocks are more than 100 m high and but 100 m down the road. 19.7.1996. perpendicular. They consist of a clayey schist Landolt 2/96. ETH Nr. 9208. without calcium carbonate (HCl test negative). 3.6 km southeast of Coroico, near San The water is relatively low in nutrient Jacinto, 1700 m a.s.l.; water fall; northeast content. The conductivity varies between 45 exposition; growing on wet rocks or and 75 |j.S cm" at the four different localities between mosses. 20.7.1996. Landolt 3/96. (64, 75, 72, 45 \iS cm"1). ETH Nr. 9209 The localities are situated within the wet 4. Road between Sta. Rosa and Undulavi, 300 tropical mountain climate; the vegetation is a m south of Velo de la Novia, 2000 m a.s.l.; tropical mountain rainforest (medio Yunga). water fall, east exposed; growing on wet Cecropia trees (Moraceae) are typical for this rock. 21.7.1996. Landolt 4/96. ETH Nr. forest as well as tree ferns. The species diversity 9210. is very high. There is no climate station We looked at other places with water falls but near the localities. However, the amount of the species was not found: along the main precipitation (2000-3000 mm year"1) is road between Chuspipata and Yolosa above estimated according to a map of Roche & Rocha 2500 m a.s.l. and below 2200 m a.s.l.; along (in Hanagarth 1993). The rain is distributed the main road between Yolosa and Caranavi throughout the year with a peak in the southern (700-1200 m a.s.l.); around Choripata and summer (December-March). During Chulumani; in the surroundings of Sorata (cf. day-time, the sky is mostly cloudy. Therefore, Fig. 2). the air humidity is always high. Temperatures There is a chance of finding the species on are relatively constant throughout the day and other wet rocks at similar altitude in the the year. The monthly means vary probably yungas between Cochabamba in the Southeast not more than 5 °C throughout the year. and Peru. However, it looks as if the species Calculated from the values of climate stations has a rather limited distribution. No along the foothills of the Andes (Rurren- herbarium specimens are known from other abaques and Villa Tunari), the mean yearly rocky places in the Andes except one from

Bulletin ofthe Geobotanical Institute ETH. 64, 15-21 17 Lemna yungensis, a new duckweed from Bolivia

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Ecuador (Prov. Pichicha, Tandapi, 1450 m muscis adhaerentibus. Lemnae valdivianae a.s.l.; growing on steep rocks by a creek, coll. valde affmis. Differì frondibus majoribus, Maas, Berg et al. 2894). Though these plants usque ad 6 mm longis et 4 mm latis, concinnis belong to the group of L. valdiviana, they are (in L. valdiviana frondes usque ad 4.5 mm morphologically different from L. yungensis; longis et 3 mm latis, parte proxima incon- they ressemble L. minuta. ditis). Flores et ffuctus incogniti. Habitat in Yunga andina Boliviae inter circa 1400 et Latin diagnosis 2500 m. Lemna yungensis spec. nov. Holotypus: La Paz, inter Chuspipata et Planta in rupibus ad perpendiculo directis Yolosa, 2440 m a.s.l. 19.7.1996. coll. E. Landolt crescens frondibus saxo humido nudo vel 1/96. LPB. Isotypus: ZT.

Bulletin ofthe Geobotanical Institute ETH. 64, 15-21 E. Landolt

Discussion both places (Rio de Janeiro and La Paz), L. valdiviana was growing in ponds and lakes of The special habitat of the species, wet, the vicinity. The regions of both places are perpendicular rocks, is very rare but not exceptional favourable for Lemnaceae growth in regard for Lemnaceae. In Landolt (1986: 140— to precipitation. The factor of Martonne 142), a survey of the known cases of amounts to 2-3 for La Paz and 3-4 for Rio de Lemnaceae growing on rocks is given. Janeiro. The factor of Martonne corresponds Lemnaceae with long roots such as L. minor to the amount of precipitation in cm divided are sometimes able to live in waterfalls, the by the temperature (°C + 10). It is a rough fronds hanging closely together by the roots measure for the average nutrient content of (known examples from Massachusetts, the regional waters. Kaukasus and the Semien mountains, Fig. 4.1 The rocks with L. yungensis are up to more in Landolt 1986). Short-rooting species than 50 m high, situated near a local waterfall. depend on slowly flowing water in order not to Lemna grows on places where the rock is get washed away. In Africa, there is an example permanently covered by a thin water coat and of L. aequinoctialis known from a river mostly sprayed by droplets from the fall. The near Brazzaville. Kolkwitz (1933) observed rock is covered with mosses and some other moist rocks near Rio de Janeiro partly plants like a Calceolaria sp. The conductivity covered with Lemna. In 1983, the present author of the water is low (45-75 pS cm" the collected L. valdiviana from steep southern precipitation very high, and the factor of exposed (shady) rocks south of Rio de Martonne amounts to 8 to >10. Lemnaceae Janeiro. The Lemna fronds stuck to the rough do not normally grow in such regions. Lemna granitic rock (Plate XVId in Landolt 1986). In yungensis is probably only able to survive on 1996, L. valdiviana was found in La Paz along waters with low nutrient content because the Avenue del Libertador near junction of Ave. water is flowing, and the plant can filter out Copacabana growing on southeast exposed the few nutrients from the permanently walls which are moistened by spring water renewed water. It seems that the plants need a (Fig. lb). The duckweeds form 14 green certain rate of water replacement to survive. stripes there. The difference in the habitat of Longer times of water shortage are detrimental. L. yungensis and L. valdiviana growing on On the other hand, the plants get washed rocks follows below. off if the water flows too rapidly. Therefore, The rocks with L. valdiviana are low in the rock wall has to be so steep that a surplus height (up to 5 m) and moistened by local of water flows directly to the ground. spring water. The mineral content of the water The new species belongs to the American is probably much higher than in the section Uninerves Hegelmaier. The two Yungas. The water of Rio de Janeiro had a known species of this section, L. valdiviana conductivity of 366 (iS cm", which is about and L. minuta, are morphologically difficult to six times higher than the average value on distinguish. The differentiation is primarily places with L. yungensis. The water of walls ecogeographic. Whereas L. valdiviana grows with L. valdiviana in La Paz was not measured. in temperate to warm tropic regions with However, the conductivity of seven relatively high air humidity, L. minuta colonizes other water samples around La Paz was primarily waters in drier regions and cannot measured between 301 and 571 \xS cm"1. In be found in the warm humid tropics. In con-

Bulletin ofthe Geobotanical Institute ETH. 64, 15-21 19 L

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Crawford, DJ., Landolt, E., Les, D.H. & Tepe, E. (1997) Allozyme variation and the taxonomy of Wolffiella. Aquatic Botany, 58, 43-54. Hanagarth, W. (1993) Acerca de la geoecologia de las sabanas del Beni en el noreste de Bolivia. Institute de Ecologia, La Paz. Kolkwitz, R. (1933) Zur Ökologie der Pflanzenwelt Brasiliens. Berichte der Deutschen Botanischen Gesellschaft, 51, 396-406. Landolt, E. (1986) The family of Lemnaceae - a monographic study. Vol. 1. Veröffentlichungen des Geobotanischen Institutes ETH, Stiftung Rubel, Zürich, 71, 1-566.

Received 12 February 1998 revised version accepted 10 March 1998

Bulletin ofthe Geobotanical Institute ETH, 64, 15-21 21