This partial translation of a bigger publication provides an identification key to the aquatic plant Hydrillae (Hydrocharitaceae) in Europe. Illustrations are included

Wolff, P.

English

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Freshwater Biological Association 
FBA Translation (New Series) No. 158 
Title: Die Hydrillae (Hydrocharitaceae) in Europa. 
(Translation of Key to Hydrillae only. pp 33-34). 
Author(s) WOLFF, P. 
Reference: Gottinger floristische Rundbriefe, 14, 33-56. 
Original language: German 
Date of publication of original: 1980 
Translator: D.F. Westlake 
Date of publication of translation: 1983 
Number of pages of translation: 4 
FBA Translations are to be considered as "provisional". As a rule 
they have not been prepared by expert translators nor have, they 
been edited by the original authors. 
They are available from The Librarian, 
Freshwater Biological Association. 
The Ferry House. 
Far Sawrey, 
AMBLESIDE 
Westmorland. 
England, 
at the current rate for xerox copying. 
FBA TRANSLATION (N.S.) No 158 
WOLFF, P. (1980) Die Hydrillae (Hydrocharitaceae) in Europa. Gottinqer 
floristische Rundbriefe, 14, 33-56. [Translation of Key to Hydrfillae only (pp 
33-34)] 
Translated by D.F. Westlake 
Notes a) The characteristic features are only valid for European 
plants. 
b) The ranges of size include both herbarium and fresh material. 
The difference can be up to 20%. 
Fibre cells are long, thick-walled scherenchyma tubes in the 
leaf margins. The leaf should be laid under the microscope 
with its underside upwards. In normal light the fibre cells 
are often difficult to see. In polarised light they appear 
as bright, luminous bands (stripes), 4—15 u across each cell, 
very distinct from the black background. 
1. Lower leaves clearly alternate; upper very close together, simulating 
whorled/verticillate, stiff, sickle-shaped and bent backwards (Fig. 9). 
Lagarosiphon major (muscoides) 
- all leaves whorled/verticillate, stiff or flaccid, bent back or 
stretched straight out. 2 
2. Middle and upper whorls with (3-)4-5(-8) leaves, no fibre cells in 
leaf margin. 3 
- middle and upper whorls with 3 leaves, only occasionally 4 near branches 
lower whorls (i.e. in spring) with 2 leaves. 1-6 fibre cell bands in 
leaf margins. 4 
Genus Elodea 
3. Leaf axils with 2 glandular, fringed scales, teeth of leaf margins 
mostly visible with the naked eye (Fig. 1); underside of mid-rib often 
with prickles or tubercules; leaves (4-) 8- 20 x 1-2 (-3) mm; cross-
section of stem 0.4-1 (-2) mm (Fig. 10). 
Hydrilla verticillata 
- leaf axil scales at most only on the youngest leaves, margins entire, 
obscure; teeth of leaf margins only visible by magnification, underside 
of leaf always smooth; leaves (10—)—15—40 x (1.5-) 2-5 mm; stems very 
robust, 0.8-3.5 mm in cross-section (Fig. 5). 
Egeria densa (Elodea) 
4. Leaves tongue-shaped i.e. with parallel margins (Fig. 3b), rarely small 
and oval (Fig. 3a), [at tips] rounded or shortly pointed; straight or 
weakly curved, however never twisted or contorted, (Fig. 7); 2-5.5 x as 
long as wide. 
Elodea canadensis (Anacharis) 
- leaves small, triangular to linear, mostly tapered equally from base to 
tip, therefore long drawn-out tips (Figs 2 & 4); straight (Figs 6 & 8c) 
or strongly bent backwards (Fig. 8a & b), in part spirally twisted; 
3.5-15 x as long as broad. 5 
5. Leaves at the most all (or only the earlier ones) strongly bent backwards 
and usually spirally twisted, rigid (Fig. 8c); rarely all leaves flat 
and flaccid; 3.5-10 x as long as wide (Fig. 2). Flowers blue-violet, 
3-5 mm across; sepals 1.2-2.4 mm long, their hooded tips violet with 
green. 
Elodea nuttallii (occidentalis) 
- leaves all flat and flaccid; 7.5-15 x as long as wide (Fig. 4 & 6). 
Flowers white, 5.5-9.5 mm across, sepals 3-4.5 mm long, their hooded 
tips green (or violet). 
Elodea ernstae (part of callitrichoides) 
Elodea callitrichoides not found in Europe; E. ernstae was identified 
as E. callitrichoides until recognised as a separate species. E.c. has 
all leaves opposite and thread-like stigmata. 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Notice 
 
 
Please note that these translations were produced to assist the scientific staff of the 
FBA (Freshwater Biological Association) in their research. These translations were 
done by scientific staff with relevant language skills and not by professional 
translators. 
 
 
 


Hydrillae (Hydrocharitaceae) in Europe. [translation of key to Hydrilla only] [Translation from: Goettinger Floristische Rundbriefe 14 33-56, 1980]

http://aquaticcommons.org/4990/1/158_1980_wolf_hydr.pdf

Hydrillae (Hydrocharitaceae) in Europe. [translation of key to Hydrilla only] [Translation from: Goettinger Floristische Rundbriefe 14 33-56, 1980]

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