Aquatic Botany 133 (2016) 17–23

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Aquatic Botany

jou rnal homepage: www.elsevier.com/locate/aquabot

The germination ecology of Helonias bullata L. (swamp pink) with

respect to dry, saturated, and flooded conditions

∗,1

April P. Punsalan , Beverly Collins, Laura E. DeWald

Department of Biology, Western Carolina University, 132 Natural Science Building, Cullowhee, NC, 28723, United States

a r t i c l e i n f o a b s t r a c t

Article history: Poor sexual recruitment is a major conservation concern for the rare obligate wetland Helonias

Received 8 October 2015

bullata L. (swamp pink). Helonias predominately occurs in forested wetlands amongst hummock-hollow

Received in revised form 12 May 2016

topography where water levels fluctuate spatially and temporally, creating a wide variety of moisture

Accepted 13 May 2016

microsite conditions for germination. To determine how moisture conditions affect the germination

Available online 13 May 2016

response of Helonias seeds, germination percentages and rates were compared after seeds were exposed

to dry, saturated (stream margin), and flooded (floating and submerged) conditions in a growth chamber

Keywords:

and field for 1–35 days. Helonias final germination percentages were greater than 50% after exposure of

Dispersal

Buoyancy all conditions, except dry conditions in the growth chamber. Moisture availability at the time of seed

arrival was the main factor that influenced the germination of Helonias. Helonias seeds exposed to satu-

Germination ecology

Hydrochory rated and flooded conditions germinated within a short time frame (10-30 days). Rapid germination may

Forested wetland be important for Helonias in forested wetlands where variable moisture conditions can create a

Rare plant narrow window for regeneration. For both the growth chamber and field experiment, final germination

Southern appalachian region

percentages were significantly higher (p < 0.05) for floating seeds compared to those kept dry. Water

Helonias bullata

likely serves as an important dispersal mechanism for Helonias seeds since they exhibit high floating

capability and germinability relative to the length of time spent in the water.

Published by Elsevier B.V.

1. Introduction of seed germination and seedling establishment (Scarano et al.,

1997; Vivian-Smith 1997; Middleton 2000). In addition, the “ger-

In forested wetlands, variations in topography create a mosaic mination window of opportunity” (Eriksson and Froborg 1996)

of microhabitats (Huenneke and Sharitz 1986; Vivian-Smith 1997; for wetland plants can be narrow or wide across both space and

Duberstein and Conner 2009; Rossell et al., 2009). Elevation, sub- time (Middleton 2000). At the narrow end, seedling recruitment for

strate variability created by accumulation of woody debris and many wetland plant species appears limited to hummocks or other

peat interwoven with tree roots, and hummock-hollow micro- emergent substrates, due to restricted germination in hypoxic con-

relief contribute to microsite diversity in these systems where the ditions in flooded hollows (Huenneke and Sharitz 1986; Huenneke

water table typically is at or above the soil surface (Ehrenfeld 1995; and Sharitz 1990; Jordan and Hartman 1995). Although many wet-

Duberstein and Conner 2009). Seasonal differences in precipitation land plants reproduce vegetatively, seed dispersal, germination,

also contribute to variability in moisture conditions (Ehrenfeld and and recruitment from seeds can aid in establishment of new pop-

Schneider 1991). ulations and maintenance of genetic diversity within populations

The spatial and temporal interactions of microtopography com- (Hawkins et al., 2011).

bined with seasonal fluctuations in hydrology produce a wide Helonias bullata L. (swamp pink) (hereafter called Helonias)

variety of moisture microsites and contribute to unpredictability is a rare obligate wetland species that occurs in forested wet-

lands from the coast of south to and into

the mountainous regions of Virginia, , South Car-

olina, and , USA (Sutter 1984). These forested wetlands,

∗

Corresponding Author. including swamps, inland stream corridors, spring seepage areas,

E-mail addresses: [email protected], april [email protected]

fens, and swamp forest-bog complexes (Murdock 1994; Dodds

(A.P. Punsalan), [email protected] (B. Collins), [email protected]

1996), typically occur at or near the beginning of streams (head-

(L.E. DeWald).

1 water streams) and are perennially wet with a water table at or

Present address: U.S. Fish and Wildlife Service, 176 Croghan Spur Road, Suite

200, Charleston, , 29407, United States. near the surface (U.S. Fish and Wildlife Service, 1991). Helonias

http://dx.doi.org/10.1016/j.aquabot.2016.05.005

0304-3770/Published by Elsevier B.V.

18 A.P. Punsalan et al. / Aquatic Botany 133 (2016) 17–23

grows along Sphagnum moss-covered stream banks and occurs the site’s sensitivity. The Pink Beds contains the largest Helonias

amongst hummock-hollow topography. Population decline and population (approximately 10,000 individuals) in North Carolina

loss of suitable habitat prompted the U.S. Fish and Wildlife Service (Sutter 1984). Helonias rosettes occur in swamp forest-bog com-

to designate Helonias as a federally threatened species under the plexes (Schafale and Weakley, 1990) located along the headwaters

Endangered Species Act in September 1988 (U.S. Fish and Wildlife of the South Fork Mills River and associated streams, small tribu-

Service, 1991). Helonias has several life history traits, including taries, and seepage areas. Rosettes typically occur on hummocks

limited inflorescence production, low seedling recruitment, and and stream banks covered with Sphagnum moss, and occasionally

restricted long distance dispersal, which contribute to the species’ in hollows or seepage areas (April Punsalan, personal observation)

vulnerability to extinction (U.S. Fish and Wildlife Service, 1991; with decomposed organic matter with silt loam underneath (Tox-

Godt et al., 1995). Although the self-compatible flowers produce oway and Hatboro soil series) (Murdock 1994). During the 2012

copious viable seeds (U.S. Fish and Wildlife Service, 1991), the seeds field study (May 30th–June 29th), the water depth in the small trib-

lose viability rapidly after several weeks (i.e., are short-lived and utary ranged from 4 to 8 cm and the average water temperature was

◦

do not appear to form a seedbank), and dispersal is limited within 16.6 C.

populations (U.S. Fish and Wildlife Service, 1991; Godt et al., 1995).

Given the high microsite heterogeneity in forested wetlands, 2.3. Seed collection

Helonias seeds could encounter a variety of moisture conditions

during their viable period. Seeds could remain dry in dehiscent We collected Helonias seeds from the Pink Beds population in

capsules or disperse along the upper, emergent portions of litter- May 2011 and 2012. We randomly selected fifteen inflorescences,

covered hummocks where drier conditions can occur (Ehrenfeld five per subpopulation, from three subpopulations approximately

1995; Vivian-Smith 1997). Alternatively, they might fall into the 0.8–1.6 km apart. Subpopulations were selected based on the high

stream channel where they could float and disperse by water and/or number of individuals and the likelihood that individuals would

sink and become submerged. Before germination, seed viability flower in 2011 and 2012. Collected seeds were mixed together to

could be jeopardized by variable periods of saturation and hypoxia produce a homogeneous seed lot and stored in the lab at room tem-

(Baskin and Baskin 1998; Lucas et al., 2012). The objective of our perature. Experiments commenced within 48 h of seed collection.

research was to determine how variable periods of dry, saturated

(stream margin), and flooded (floating or submerged) conditions 2.4. Growth chamber experiment

affect the germination response (percentages and rates) of Helo-

nias. In a growth chamber experiment, seeds were subjected to To determine the germination response of Helonias seeds after

dry, floating, and submerged conditions for 1–35 days. In addition, exposure to different moisture conditions, seeds were (1) kept dry

a field experiment was conducted in a small headwater stream to (dry), (2) placed floating in water (floating), or (3) submerged in

test the germination response of seeds placed in dry (out of water), water (submerged). For each moisture condition, six replicates of

saturated (stream margin) and flooded (floating or submerged in 200 seeds were used. For dry conditions, seeds were placed in cylin-

stream) conditions for 1–30 days. We compared the germination drical 88 ml glass containers with no water. Floating seeds were

response (germination percentages) and the breadth of the ‘germi- placed in 946 ml round glass containers (14 cm diameter) filled

nation window’ over time (germination rates) among the moisture with distilled water, which was maintained at 6 cm water depth.

conditions in each experiment. In addition, we examined the length Submerged seeds were placed in nylon mesh bags weighted with

of time seeds float and maintain germinability when submersed or marbles and submerged beneath 5 cm of distilled water in 946 ml

floating in order to assess the potential for water dispersal. glass containers (12 cm x 12 cm x 6 cm high). Containers were repo-

sitioned daily in growth chambers to exclude position effects and

water was added daily to maintain water depths. The study was

2. Methods

conducted in one growth chamber at 60% relative humidity at

◦ −2 −1

27.7 C for 14 h. daylight at a photon flux of 670 ␮m m s and

2.1. Species description ◦

14.4 C for 10 h. darkness to approximate average field conditions

in Transylvania County for June.

Helonias bullata is a “petaloid lilioid monocot” that belongs to

We defined eight time intervals to measure germination

the order , family s.l. (sensu lato) (Zomlefer

response after exposure to moisture conditions: 1, 2, 3, 5, 8, 13,

et al., 2001). Helonias is an herbaceous perennial with evergreen

21, and 35 days. After each time interval, six replicates of 25 seeds

oblong-spatulate leaves that form a basal rosette (Godfrey and

were removed to test germination rates and percentages. Seeds

Wooten 1979; U.S. Fish and Wildlife Service, 1991). Flower pro-

were placed in petri dishes (25 seeds per dish/six replicates) on

duction occurs from March to May with peak bloom in mid-April.

top of a soil mixture (3 parts peat moss: 2 parts milled sphagnum:

Helonias produces a fragrant, terminal raceme composed of 30–50

1 part builder’s sand) (Ron Determann, personal communication).

perfect individual flowers (Sutter 1984) with pink and dis-

Petri dishes were checked daily for moisture content and kept satu-

tinctive blue anthers. Each flower matures into a dehiscent capsule

rated for a 50-day germination period. On a daily basis, germination

that contains approximately 25–35 individual seeds. During flower

(determined by 1 mm radicle emergence) was recorded and germi-

development, Helonias has a hollow scape approximately 2–9 dm

nants were removed. Seeds that were moldy, mushy, or shriveled

tall that grows to a height of 1.5 m during seed maturation. Capsules

were removed from dishes. A soil mixture was used for the growth

mature and release seeds in late May/early June (Chafin 2007). Ripe

chamber experiment instead of Whatman #1 filter paper to prevent

seeds are linear, 5 mm long, and have a fatty or caudal appendage

radicle or root defects thereby increasing the likelihood germinants

along the entire seed edge (U.S. Fish and Wildlife Service, 1991).

could be used for ex situ conservation.

2.2. Study site 2.5. Field experiment

We conducted this study in the southern Appalachian region in In 2012, the germination response of Helonias seeds after expo-

a small tributary within the Pink Beds recreational area (elevation sure to different moisture conditions in the field was tested in dry,

980 m) in the Pisgah National Forest, Transylvania County, North saturated (stream margin), floating, and submerged treatments in

Carolina, USA. Geographical coordinates are withheld because of a small stream within the Pink Beds. The stream margin treat-

A.P. Punsalan et al. / Aquatic Botany 133 (2016) 17–23 19

ment was considered ‘saturated’ because the ground water table 120

and the stream bottom are almost equal; the entire soil column a

100

remains saturated most of the year (Brady Dodd, personal commu- a

nication). Seeds were exposed to atmospheric moisture (i.e., rain

80

or humidity) for the ‘dry’ treatment, but were not exposed to direct b

moisture conditions. For each treatment and time interval (1, 3, 5,

60

8, 12, 16, 20, and 30 days), six replicates of 25 seeds were placed

into a polystyrene ring/container constructed from the bottom of

Germination % Germination 40

a 236 ml Styrofoam cup. Nylon mesh was placed around each con-

tainer and fastened with a zip tie. The containers were tied to pin 20

flags (four treatments/containers per pin flag) and placed in the

stream (water depth: 4–8 cm). Containers for the dry treatment 0

were kept above the water by attaching them directly to the top Dry Floating Submerged

Treatment

of the pin flag. For the saturated treatment, containers were posi-

tioned on the pin flag below the dry treatment and placed in the

Fig. 1. Helonias bullata final germination percentages (mean ± S.D.) after exposure

stream margin using fishing line. To secure the containers along the

to three treatments (dry, floating, and submerged) in a growth chamber. Post hoc

stream margin, marbles were placed inside containers for weight. comparisons between treatments were made using Bonferroni t-tests (p < 0.05).

The floating treatment containers were attached to the pin flags Significant differences (F2,15 = 28.21; p = 0.0001) in final germination percentages

among treatments are indicated by different lowercase letters.

below the stream margin treatment and placed in the stream with

fishing line. The polystyrene ring kept the containers buoyant for

the entire study. Containers for the submerged treatment were

placed at the bottom of the pin flag under 4–8 cm of water (average

water depth was 5 cm); marbles were placed inside the containers

for weight.

At each time interval, one replicate (i.e., container) for each

treatment were removed from the stream, placed in plastic bags,

and taken to the growth chamber to test germination percent-

ages and rates. Because seeds were in natural field conditions and

possibly exposed to fungi and/or bacteria, seeds removed from con-

tainers were sanitized using a 2% hypochlorite solution and rinsed

three times with deionized water to remove potential microor-

ganism contamination. Seeds (25) were placed in petri dishes on

Whatman filter paper. Seeds from all treatments were germinated

◦

in one growth chamber at 27.7 C for 14 h. daylight at a photon flux

−2 −1 ◦

of 670 ␮m m s and 14.4 C for 10 h. darkness at 60% humidity

for a 30-day germination period. On a daily basis, germinated seeds

were recorded and removed when a radicle 1 mm emerged. Dishes

were checked every other day for moisture content and kept satu-

rated. Seeds that were moldy, mushy, or shriveled were removed

from dishes.

Fig. 2. Final germination percentages (mean ± S.D.) of Helonias bullata seeds after

2.6. Data analyses

exposure to dry conditions in a growth chamber. Post hoc comparisons between days

were made using Bonferroni t-tests (p < 0.05). Significant differences (F7,40 = 36.46;

p = 0.0001) in final germination percentages among dry exposure are indicated by

Final germination percentages (seeds germinated/total number

different lowercase letters.

of seeds x 100) were calculated at the end of germination periods.

Germination rates were calculated at 5-day intervals by dividing

(SAS Institute, 2008). Non-transformed germination percentages

the cumulative number of germinated seeds by the total number

are displayed for results.

of seeds placed in a petri dish (25). Germination rates were plotted

against time to examine the relationship between the length of time

in treatment and the timing of germination. 3. Results

To determine how moisture conditions affected the germina-

tion response of Helonias seeds after different periods of time, 3.1. Growth chamber experiment

analysis of variance (ANOVA) was used to compare final mean ger-

mination percentages among treatments and time intervals. Data Final germination percentages were significantly (F2,15 = 28.21,

(percentages) were arcsine transformed to conform to normal- p = 0.0001) affected by treatment (dry, floating, and submerged)

ity, but actual values were used for figures. Post hoc comparisons (Fig. 1). Comparisons among treatments revealed that seeds in

± ±

between treatment type and days in treatment were made using the floating (78 19%) and submerged (76 18%) treatments had

±

Bonferroni t-tests (p < 0.05) (SAS Institute, 2008). Throughout, we significantly higher germination than seeds kept dry (47 16%)

report means ± 1 standard deviation. (Fig. 1).

To determine how moisture conditions affected the germina- Exposure of Helonias seeds to dry conditions for longer than

tion rate of Helonias seeds after different time periods, a repeated five days significantly (F7,40 = 36.46, p = 0.0001) decreased final

measures analysis of variance (RMANOVA; mixed model proce- germination (Fig. 2). Further, germination decreased with longer

dure) was performed to compare cumulative mean germination exposure to dry conditions; seeds dry for eight days, 13 days, and

± ± ±

percentages at 5-day intervals. SAS 9.2 was used for all analyses 21 days germinated to 25 15%, 17 11%, and 3 2%, respectively

20 A.P. Punsalan et al. / Aquatic Botany 133 (2016) 17–23

Table 1

Results of RMANOVAs comparing Helonias bullata mean cumulative germination

over days within moisture treatments in growth chamber and field experiments.

Experiment NumeratorDF DenominatorDF F Value Pr>F

Growth Chamber

Dry 7 40 11.69 <0.0001

Floating 4 25 12.43 <0.0001

Submerged 4 25 3.76 <0.016

Field

Dry 5 35 142.56 <0.0001

Saturated 6 35 96.35 <0.0001

Floating 6 35 125.80 <0.0001

Submerged 6 35 94.16 <0.0001

Fig. 4. Helonias bullata final germination percentages (mean ± S.D.) after exposure

to four treatments (dry, saturated (i.e., stream margin), floating, and submerged) in

a field experiment in Transylvania County, North Carolina. Significant differences

(F3,20 = 6.77; p = 0.0002) between final mean germination percentages among treat-

ments are indicated by different lowercase letters (determined by Bonferroni t-tests,

p < 0.05).

the floating treatment to determine buoyancy potential. However,

final germination percentages and rates were compared for seeds

floating for less than 13 days (i.e., 1, 2, 3, 5, and 8 days). Floating

duration (1, 2, 3, 5, and 8 days) did not significantly (F4,25 = 2.01,

p = 0.12) affect final germination percentages of Helonias seeds.

Mean germination was high (78 ± 19%) irrespective of the length of

time seeds floated. However, the length of time seeds floated sig-

nificantly affected the germination rate of Helonias seeds (Table 1).

Seeds that floated for eight days germinated to 65 ± 24% after five

days whereas seeds that floated on water for only one day took

45 days to reach 65 ± 18% germination (Fig. 3). After 21 days, 100%

of seeds had germinated while floating. Additionally, at day 21,

germinated seeds developed a cotyledon and primary root axis

approximately 2 cm long; 94% of seedlings were still floating after

35 days.

After 13 days, 77% of seeds germinated while submerged; these

germinants were counted and removed from treatment. Thus, final

germination percentages and rates were only compared among

seeds submerged for 1, 2, 3, 5, and 8 days. Mean germination

was high (76 ± 18%) irrespective of the length of time seeds were

submerged. However, the length of time seeds were submerged sig-

nificantly affected the germination rate of Helonias seeds (Table 1).

Seeds submerged for eight days germinated to 63% ± 21% after five

days (Fig. 3). In contrast, seeds that had been submerged for only

one day took 35 days to germinate to 47 ± 10% (Fig. 3).

3.2. Field experiment

Final germination percentages were significantly (F3,20 = 6.77,

p = 0.0002) affected by treatment (dry, saturated, floating, and sub-

merged) (Fig. 4). Comparisons among treatments revealed that

Fig. 3. Cumulative germination (%) of Helonias bullata seeds over time (days) after

seeds that had floated in the stream had significantly higher final

different lengths of time (1, 3, 5, 8, 13, 21, 35 days) in dry, submerged, or floating

± ±

conditions. germination (82 9%) than seeds kept ‘dry’ (59 6%) (Fig. 4).

Results from the RMANOVAs revealed that the length of time seeds

were in each treatment significantly affected their germination

(Fig. 2). Seeds exposed to dry conditions for 35 days did not germi- rate (Table 1). After 20 days in the floating, saturated, and sub-

nate (Fig. 2). Helonias germination rates in the dry treatment also merged treatments, germination onset occurred in situ or while

differed with time in treatment (Table 1). Seeds in dry conditions seeds were in the field. After 20 days, 49 ± 37% of seeds germi-

for 8–21 days took over 20 days to begin germinating (Fig. 3). nated in the stream margin; 58 ± 1% germinated while floating in

After 13 days of floating on distilled water, 90% of seeds germi- the stream; and 3 ± 0.05% germinated while submerged (Fig. 5).

nated while floating. We decided to keep the germinated seeds in After 30 days, 79 ± 21% of floating seeds and 77 ± 23% of seeds in the

A.P. Punsalan et al. / Aquatic Botany 133 (2016) 17–23 21

of dormancy and early germination at the start of the growth sea-

son increased the likelihood that seedlings of Hottonia palustris L.,

another spring flowering, forested wetland perennial, established

successfully (Brock et al., 1989). Early germination for forested

wetland plants can also ensure that seedling establishment coin-

cides with summer drawdown or the terrestrial phase (Wittmann

et al., 2007). In forested wetlands, Helonias occurs in areas where

water levels range from slightly higher to flooded mid-winter to

mid-summer and lower late summer and fall (Laidig et al., 2009),

with seasonal high moisture availability occurring in early spring

(Ehrenfeld and Schneider 1991). Thus, dispersal and rapid germina-

tion in the spring may be a regeneration strategy that increases the

likelihood that dispersed Helonias seeds arrive in saturated con-

ditions conducive for germination and seedlings establish during

summer drawdown or when water levels recede.

For both the growth chamber and field experiment, buoyant

seeds had significantly higher final germination percentages than

dry seeds. In addition, after 20 days, seeds submerged (3%), floating

(58%), and in the saturated stream margin (49%) germinated in situ,

whereas no germination occurred for seeds in the ‘dry’ treatment in

the field. Thus, saturated and flooded conditions did not inhibit ger-

mination, but on the contrary, enhanced germination. Our results

demonstrate that seeds that ‘land’ or disperse to saturated con-

ditions such as Sphagnum-covered stream banks or hummocks,

and flooded conditions such as hollows, stream channels, or seep-

age areas will germinate rapidly, within 10–30 days. In contrast,

because Helonias seeds lose viability rapidly over time (Perullo et al.

2015), and require moisture for imbibition and likely for embryo

growth, germination and subsequent establishment will unlikely

occur on dry elevated forested areas or on emergent litter-covered

hummocks with limited moisture availability. Seeds that disperse

via water may have higher germination rates than gravity or wind

dispersed seeds because water or moisture required for imbibition

and embryo growth may occur during transport. Although only a

few Helonias seeds germinated while submerged in the stream, final

germination percentages were high (>70%) for seeds exposed to

submerged conditions for 1-30 days. As such, Helonias seeds sub-

Fig. 5. Cumulative germination (%) of Helonias bullata seeds over time (days) after

merged in hollows, spring seepage areas, or streams could remain

different lengths of time (1, 3, 5, 8, 12, 16, 20, 30 days) in dry, saturated, submerged,

viable for up to 30 days and germinate once water levels recede

or floating conditions in the field.

or suitable conditions arise. Overall, the germination responses of

Helonias, including early and enhanced germination in saturated

stream margin had developed a cotyledon and primary root length

and flooded conditions, demonstrate a close link between regener-

of approximately 3–5 cm while in treatment. Conversely, germi-

ation from seeds and the hydric conditions of forested wetlands.

nation onset did not occur for seeds in the dry treatment in situ;

germination onset occurred after 15 days of exposure to moisture

4.2. Floating capability and water dispersal

conditions in the growth chamber (Fig. 5)

Helonias exhibited high floating capability; 94% of seeds

4. Discussion remained buoyant for the length of the study (35 days) in the

growth chamber. The high floating capability of Helonias seeds may

4.1. Helonias germination window and response to moisture increase the probability they deposit on ‘safe sites’ for germina-

conditions tion, i.e., on moist substrates but not underwater. The ability of

Taxodium distichum (L.) Rich. and Nyssa aquatica L. seeds to float for

Helonias seeds enlarged in size shortly after being exposed to 2–3 months increased the probability seeds deposited on elevated

water (saturated, floating, or submerged treatments), and more microsites favorable for germination and seedling establishment

than 50% of seeds exposed to saturated or flooded conditions in the (Demaree 1932; Dubarry 1963; Schneider and Sharitz 1988). In

growth chamber or field germinated in a small temporal window forested wetlands, buoyant seeds typically concentrate near emer-

(10–30 days). Similarly, Perullo et al. (2015) reported that Helonias gent substrates such as logs, knees, and tree bases (Schneider

seeds germinated after one week and maximum percent germi- and Sharitz 1988). Helonias seeds released within a headwater

nation occurred after three to four weeks. Together, these results stream dispersed downstream and collectively concentrated near

suggest Helonias seeds either lack dormancy or, like many species a fallen log and floating debris (April Punsalan, personal observa-

within the family Melanthiaceae, have a short period of morpholog- tion). Emergent substrates, such as Sphagnum-covered hummocks,

ical dormancy (i.e., underdeveloped embryos) that is overcome by likely serve as ideal catchment sites for buoyant Helonias seeds. In

water exposure (Baskin and Baskin 1998). Rapid germination dur- the southern Appalachian region, Sutter (1984) reported that wind

ing favorable moisture conditions may be important for Helonias in unlikely disperses Helonias seeds greater than 40 cm in distance. As

forested wetlands where spatially and temporally variable mois- Helonias rosettes typically occur along and within stream channels

ture conditions can create a narrow window for regeneration. Lack (Laidig et al., 2009), water may serve as a more effective disper-

22 A.P. Punsalan et al. / Aquatic Botany 133 (2016) 17–23

sal agent than wind or gravity by dispersing Helonias seeds further ney Wiest for their support, knowledge, and expertise. We would

distances and by providing needed moisture for imbibition. like to thank Jonathan Horton for allowing us to use the growth

In both the growth chamber and field, floating seeds germi- chambers at University of North Carolina at Asheville. The Gar-

nated and formed a cotyledon and primary root after 21 and 30 den Club of America, Catherine H. Beattie Fellowship, financially

days, respectively. Such floating “seedling banks” (Scarano 1998) supported this research.

have been observed in other emergent wetland plants such as Oron-

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