The Genus Isoetes (Lycophyta) in the Southeastern United States Lytton John Musselman, Rebecca D Bray W Carl Taylor 10 April 2007.

Presentation on theme: "The Genus Isoetes (Lycophyta) in the Southeastern United States Lytton John Musselman, Rebecca D Bray W Carl Taylor 10 April 2007."— Presentation transcript:

1 The Genus Isoetes (Lycophyta) in the Southeastern United States Lytton John Musselman, Rebecca D Bray W Carl Taylor 10 April 2007

2 The Genus Isoetes (Lycophyta) in the Southeastern United States A quarter century review for field botanists

3 What is a quillwort? Field characters

4 Obligate 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

5 Obligate hydrophyte with spirally arranged leaves

6 groove on adaxial surface, four air chambers

7 groove on adaxial surface, four air chambers

8 groove on adaxial surface, four air chambers diaphragm

9 arising from a “corm-like” structure bearing forked root tips

10 All quillworts look similar! Size can range from 0.01 to 2.0 m Isoetes butleriIsoetes melanopodaIsoetes mattaponica

11 All quillworts look similar! Isoetes butleri Kentucky Isoetes stellebossiensis South Africa Isoetes olympica Syria

12 All quillworts look similar! Lots of variability in size in most species Isoetes hyemalis TerrestrialSubmersed

13 The exception to the spiraled leaves, corm structure, and forked roots is Isoetes tegetiformans

14 Then and Now 1985--Three species of quillworts in Flora of the Carolinas 2007--Six in Weakley

15 Then and Now 1985--No hybrids 2007--Isoetes are

16 Then and Now 1985--No hybrids 2007--Isoetes are Promiscuous all can be expected to hybridize

17 Then and Now 1985--few species with scales 2007-- all Isoetes have scales

18 Then and Now 1985--few species with scales 2007-- all Isoetes have scales

19 Scales and Phyllopodia are Different Scales are modified leaves, phyllopodia are indurated leaf bases

20 Then and Now 1985--considered infrequent or rare 2007-- most counties in the Southeast probably have/had Isoetes

21 Then and Now 1985--little vegetative reproduction 2007-- probably widespread

22 Then 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

23 Then and Now 1985--Megaspores essential for determination 2007-- Megaspores still necessary for diploid species

24 Megaspores confusing for most tetraploids because of similar ornamentation Isoetes georgiana Isoetes hyemalis

25 The Genus as Currently Understood Taxonomically in the Southeast I. Nine Basic Diploids (2n=22) Isoetes butleri I. engelmannii I. flaccida I. mattaponica I. melanopoda I. melanospora I. “piedmontana’ I. tegetiformans I. valida

26 The Genus as Currently Understood I. Basic Diploids (2n=22) Conservation concern I. mattaponica I.melanospora I. tegetiformans

27 Isoetes acadiensis I. appalachiana I. hyemalis I. louisianensis I. piedmontana I. riparia I. virginica The Genus as Currently Understood II. Seven Described Allotetraploids (2n=44)

28 II. Allotetraploids (2n=44) Conservation concerns Cannot be accurately addressed until we know more about the phylogeny of these polyploids, at least some of which are polyphyletic The Genus as Currently Understood

29 III. Three Described Allohexaploids (2n=66) Isoetes georgiana (includes I. boomii) I. junciformis I. microvela The Genus as Currently Understood

30 IV. Allohexaploids (2n=66) Conservation concerns Cannot be accurately addressed until we know more about the phylogeny of these polyploids, at least some of which might be polyphyletic The Genus as Currently Understood

31 IV. One Allooctoploid (2n=88) Isoetes tennesseensis of conservation concern The Genus as Currently Understood

32 V. One Allodecaploid (2n=110) Isoetes lacustris Of conservation concern in the South, abundant across Canada The Genus as Currently Understood

33 VI. Four named primary hybrids Isoetes × altonharvillii (I. valida x I. engelmannii, 2n=22) I. × brittonii (I. engelmannii x I. riparia, 2n=33) I. × bruntonii (I. engelmannii x I. hyemalis, 2n=33) I. × carltaylorii (I. engelmannii x I. acadiensis, 2n=33) The Genus as Currently Understood

34 Hybrids spores are misshapen and of varying sizes

35 Hybrids exhibit heterosis Isoetes valida Isoetes engelmannii Isoetes × altonharvillii

36 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. The Genus as Currently Understood

37 How are Isoetes species identified?

38 Answer: With difficulty!

39 Megaspores have traditionally been the most reliable way to identify quillworts

40 Until the advent of molecular techniques, megaspores were used to suggest patterns of phylogeny

41 How many species have been extirpated in the past twenty five years? Isoetes “riparia”, Alligator River, North Carolina

42 Acknowledgements 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