Title: The Genus Isoetes (Lycophyta) in the
1The Genus Isoetes (Lycophyta) in the Southeastern
United States
Lytton John Musselman, Rebecca D Bray W Carl
Taylor
10 April 2007
2The Genus Isoetes (Lycophyta) in the Southeastern
United States
A quarter century review for field botanists
3What is a quillwort? Field characters
4Obligate hydrophyte with spirally arranged leaves
with a groove on the adaxial surface, four air
chambers arising from a corm-like structure
bearing forked root tips
5Obligate hydrophyte with spirally arranged leaves
6groove on adaxial surface, four air chambers
7groove on adaxial surface, four air chambers
8diaphragm
groove on adaxial surface, four air chambers
9arising from a corm-like structure bearing
forked root tips
10All quillworts look similar! Size can range from
0.01 to 2.0 m
Isoetes butleri
Isoetes melanopoda
Isoetes mattaponica
11All quillworts look similar!
Isoetes butleri Kentucky
Isoetes stellebossiensis South Africa
Isoetes olympica Syria
12All quillworts look similar! Lots of variability
in size in most species
Isoetes hyemalis
Terrestrial
Submersed
13The exception to the spiraled leaves, corm
structure, and forked roots is Isoetes
tegetiformans
14Then and Now 1985--Three species of quillworts
in Flora of the Carolinas 2007--Six in Weakley
15Then and Now 1985--No hybrids 2007--Isoetes are
16Then and Now 1985--No hybrids 2007--Isoetes are
Promiscuous all can be expected to hybridize
17Then and Now 1985--few species with
scales 2007-- all Isoetes have scales
18Then and Now 1985--few species with
scales 2007-- all Isoetes have scales
19Scales and Phyllopodia are Different Scales are
modified leaves, phyllopodia are indurated leaf
bases
20Then and Now 1985--considered infrequent or
rare 2007-- most counties in the
Southeast probably have/had Isoetes
21Then and Now 1985--little vegetative
reproduction 2007-- probably widespread
22Then and Now 1985--little vegetative
reproduction 2007-- probably widespread
through branching of the root stock
Isoetes flaccida, Putnam Co, FL
Unnamed tetraploid, Chesterfield Co, VA
23Then and Now 1985--Megaspores essential for
determination 2007-- Megaspores still necessary
for diploid species
24Megaspores confusing for most tetraploids
because of similar ornamentation
Isoetes hyemalis
Isoetes georgiana
25The Genus as Currently Understood Taxonomically
in the Southeast I. Nine Basic Diploids (2n22)
Isoetes butleri I. engelmannii I. flaccida I.
mattaponica I. melanopoda I. melanospora I.
piedmontana I. tegetiformans I. valida
26The Genus as Currently Understood
- I. Basic Diploids (2n22)
- Conservation concern
- I. mattaponica
- melanospora
- I. tegetiformans
27The Genus as Currently Understood II. Seven
Described Allotetraploids (2n44)
Isoetes acadiensis I. appalachiana I. hyemalis
I. louisianensis I. piedmontana I. riparia I.
virginica
28The Genus as Currently Understood
II. Allotetraploids (2n44) Conservation
concerns Cannot be accurately addressed until we
know more about the phylogeny of these
polyploids, at least some of which are
polyphyletic
29The Genus as Currently Understood
III. Three Described Allohexaploids
(2n66) Isoetes georgiana (includes I. boomii)
I. junciformis I. microvela
30The Genus as Currently Understood
IV. Allohexaploids (2n66) Conservation
concerns Cannot be accurately addressed until we
know more about the phylogeny of these
polyploids, at least some of which might be
polyphyletic
31The Genus as Currently Understood
IV. One Allooctoploid (2n88) Isoetes
tennesseensis of conservation concern
32The Genus as Currently Understood
V. One Allodecaploid (2n110) Isoetes lacustris
Of conservation concern in the South, abundant
across Canada
33The Genus as Currently Understood
- VI. Four named primary hybrids
-
- Isoetes altonharvillii (I. valida x I.
- engelmannii, 2n22)
-
- I. brittonii (I. engelmannii x I. riparia,
- 2n33)
- I. bruntonii (I. engelmannii x I. hyemalis,
- 2n33)
- I. carltaylorii (I. engelmannii x I.
acadiensis, - 2n33)
34Hybrids spores are misshapen and of varying sizes
35Hybrids exhibit heterosis
Isoetes altonharvillii
Isoetes valida
Isoetes engelmannii
36The Genus as Currently Understood
VI. New Taxa There are several diploid
populations that deserve further study, these
could be new species. We have several distinct
tetraploid populations but cannot formally name
them until we understand their phylogeny.
37How are Isoetes species identified?
38Answer With difficulty!
39Megaspores have traditionally been the most
reliable way to identify quillworts
40Until the advent of molecular techniques, megaspor
es were used to suggest patterns of phylogeny
41How many species have been extirpated in the past
twenty five years?
Isoetes riparia, Alligator River, North Carolina
42Acknowledgements Khalid Al Arid Mohammad Al
Zein Jim Allison Jay Bolin Daniel Brunton Cindy
Caplen Kerry Heafner Jim Hickey David Knepper ODU
Plant Research Group Charlie Werth Joe Winstead