Kawai Nui Marsh / sediment cores / peat layer seeds from lagoonal facies

Floral Recoveries from the Lagoonal Facies
Kawai Nui Marsh, O`ahu

Robert Moye, HPU

Numerous seeds have been collected from sediments beneath Kawai Nui Marsh during the present (2001) round of auger sampling. These seeds come from sediments lying directly above the basal open marine bay deposits [see reef facies ], including about 10 cm interpreted as lagoonal mud and peaty deposits thought to be the oldest marsh sediments.
There are five distinct seed types commonly present (see below). Heidi Lennstron at the Bishop Museum has identified three as Potamogeton foliosus (leafy pond weed) of the Family Potamogetonaceae, Ruppia maritima (ditch weed or widgeon grass) of the Family Ruppiaceae, and the great bulrush, Schoenoplectus lacustris. All are indigenous wetland species. Two more seed types remain unidentified.
We are starting to get some idea of the lagoon margin plant community. It was probably not too dissimilar from the Nu`upia Ponds on the Mokapu Peninsula. In addition, single seeds were recovered from two samples that may be from a pre-contact gourd. We did find several gourd fragments in one sample. We also recovered a kukui nut from lagoonal(?) sediments only 2 cm above the open marine deposits.

Identification of seeds in peat layer core samples taken in Kawai Nui Marsh provides insights into the changing patterns of vegetation in and around this wetland environment over the last ~1500 years. Shown here are the most common seeds encountered in the prehistoric peat, with a brief description of the plant and where it might grow.

ditchgrass or widgeon grass
  Seeds of widgeon grass (Ruppia maritima). This indigenous aquatic plant grows completely submerged in brackish or subsaline water, typically near the coast. Nearby, Pa`akai Pond (Nu`upia, MCBH) sometime harbors widgeon grass when salinity drops into the 20-23 ppt range.

  Seeds (achenes) of `aka`akai or great bulrush, Schoenoplectus lacustris, an emergent wetland plant of lowland fresh and brackish water marshes. Bulrush found in Kawai Nui today is mostly S. californicus, a closely related species usually listed as introduced to Hawai`i, which may be native (indigenous) as well.

  Seeds (achenes) of the leafy pondweed (Potamogeton foliosus). This indigenous aquatic plant grows completely submerged in streams, irrigation ditches, and lo`i kalo.

unidentified seed
  This seed is present in the peat cores, but has not yet been identified.

Kukui tree seed
  A large nut of the kukui tree (Aleurites moluccana). Whole seeds and hulls are found in small numbers in the peat layer down to just above the clay layer, suggesting the presence of this forest tree along the shore or in upstream tributaries throughout the time period of peat formation. The kukui tree was brought to the Hawaiian Islands by Polynesians, presumably around 400-500 AD.

unknown gourd seeds
  Seeds of an unknown species of Cucurbitaceae, possibly a type of gourd. So far, these are the only two seeds of this type found in the core samples.

[KO`OLAU NET] | [AHUPUA`A] | [`Ahahui Malama I Ka Lokahi]

	Numerous seeds have been collected from sediments beneath Kawai Nui Marsh during the present (2001) round of auger sampling. These seeds come from sediments lying directly above the basal open marine bay deposits [see reef facies ], including about 10 cm interpreted as lagoonal mud and peaty deposits thought to be the oldest marsh sediments. There are five distinct seed types commonly present (see below). Heidi Lennstron at the Bishop Museum has identified three as Potamogeton foliosus (leafy pond weed) of the Family Potamogetonaceae, Ruppia maritima (ditch weed or widgeon grass) of the Family Ruppiaceae, and the great bulrush, Schoenoplectus lacustris. All are indigenous wetland species. Two more seed types remain unidentified. We are starting to get some idea of the lagoon margin plant community. It was probably not too dissimilar from the Nu`upia Ponds on the Mokapu Peninsula. In addition, single seeds were recovered from two samples that may be from a pre-contact gourd. We did find several gourd fragments in one sample. We also recovered a kukui nut from lagoonal(?) sediments only 2 cm above the open marine deposits. Identification of seeds in peat layer core samples taken in Kawai Nui Marsh provides insights into the changing patterns of vegetation in and around this wetland environment over the last ~1500 years. Shown here are the most common seeds encountered in the prehistoric peat, with a brief description of the plant and where it might grow.
		Seeds of widgeon grass (Ruppia maritima). This indigenous aquatic plant grows completely submerged in brackish or subsaline water, typically near the coast. Nearby, Pa`akai Pond (Nu`upia, MCBH) sometime harbors widgeon grass when salinity drops into the 20-23 ppt range.
		Seeds (achenes) of `aka`akai or great bulrush, Schoenoplectus lacustris, an emergent wetland plant of lowland fresh and brackish water marshes. Bulrush found in Kawai Nui today is mostly S. californicus, a closely related species usually listed as introduced to Hawai`i, which may be native (indigenous) as well.
		Seeds (achenes) of the leafy pondweed (Potamogeton foliosus). This indigenous aquatic plant grows completely submerged in streams, irrigation ditches, and lo`i kalo.
		This seed is present in the peat cores, but has not yet been identified.
		A large nut of the kukui tree (Aleurites moluccana). Whole seeds and hulls are found in small numbers in the peat layer down to just above the clay layer, suggesting the presence of this forest tree along the shore or in upstream tributaries throughout the time period of peat formation. The kukui tree was brought to the Hawaiian Islands by Polynesians, presumably around 400-500 AD.
		Seeds of an unknown species of Cucurbitaceae, possibly a type of gourd. So far, these are the only two seeds of this type found in the core samples.