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© W.P. Armstrong (Updated 9 November 2021)
Abeja Pond Northwest Of Owens Peak (Part 1)
    Abeja Pond Part 2  
 OwensPk1   OwensPk2A   OwensPk2B   OwensPk3   OwensPk4   OwensPk5   OwensPk6   OwensPk7   AbejaPond 

Abeja Pond is located in a small, undeveloped valley of coastal sage scrub, chaparral and freshwater marsh northwest of Owens Peak. Like Owens Peak, it is surrounded by housing developments and is threatened by land developers and the City of San Marcos. Many bryophytes and lichens occur on hills to the east, particularly on shady banks along trails leading to the north side of Owens Peak. Like the cryptobiotic crust of desert areas, these minute plants are fragile and vulnerable to foot traffic, bicycles and motorized vehicles (see Owens Peak 7). Many animals have been reported from this valley, including bobcat and mountain lion. The mountain lion sightings were at the north end of valley near Buena Creek Road. I can personally vouch for the reliable testimony of one mountain lion observer. It is imperative that this valley remain an open wildlife corridor.

Duckweeds: Family Araceae--Subfamily Lemnoideae

Abeja Pond photographed in January 2020.

Another small pond west of Abeja Pond surrounded by thickets of cattails (Typha), bulrushes (Scirpus) and willows (Salix). Note: The common bulrushes (Scirpus californicus & S. acutus) have now been placed in the genus Schoenoplectus.

Mallard mother & two ducklings.

Duckweeds (Lemna) taken from shore of Abeja Pond.

Close-up view of 2 species of duckweed (Lemna) in Abeja Pond.

Ducks & Coots (Mud Hens) are attracted to duckweed populations. This mass is predominantly Lemna minuta mixed with some L. turionifera and a few Wolffia globosa.

Marsh fleabane (Pluchea odorata var. odorata). The genus Pluchea also includes arrow-weed (P. sericea) the common desert plant forming thickets in riverbeds and marsh areas.

Abeja Pond Revisited 21 Oct 2020

Found One Wolffia globosa: World's Smallest Flowering Plant!

According to the Kew Plant List there are an estimated 352,000 species of flowering plants in the world, and they range in size from diminutive alpine daisies only a few inches tall to massive eucalyptus trees in Australia over 300 feet tall. But the undisputed world's smallest flowering plants belong to the genus Wolffia, minute rootless plants of the duckweed subfamily (Lemnoideae) that float at the surface of quiet streams and ponds. Each plant is shaped like a microscopic green football with a flat or rounded top depending on the species. They reproduce exponentially by budding, and during warm summer months they literally cover the water surface like masses of granular, green Malto-Meal. Two of the smallest species are W. angusta, an Australian species described in 1980 by Dr. Elias Landolt, and the worldwide tropical species W. globosa. The entire plant body of these two species is less than one mm long (less than 1/25th of an inch) and it is difficult to say which is the smaller of the two, but perhaps W. globosa may be slightly smaller. An average individual plant is 0.6 - 0.8 mm long (1/42 of an inch) and 0.3 mm wide (1/85th of an inch). It weighs about 150 micrograms (1/190,000 of an ounce), or the approximate weight of two ordinary grains of table salt. One plant is 165,000 times shorter than the tallest Australian eucalyptus tree and 7 trillion times lighter than the most massive giant sequoia tree. It is small enough to slip through the eye of an ordinary sewing needle, and at least 5,000 plants could be packed into a thimble. I once submited Wolffia to the Guinness Book & replaced their previous incorrect record! Each plant produces a microscopic flower inside a small cavity that develops on the upper side of the plant body. The minute flower consists of a single pistil and stamen. Since the stigma is generally receptive before the anther is mature, a condition known as protogyny, the flower typically requires cross pollination from a different wolffia plant with a mature anther that is ready to shed its pollen. A bouquet of one dozen plants in full bloom will easily fit on the head of a pin. After pollination the ovary develops into a tiny one-seeded fruit called a utricle, which also holds the record for the world's smallest fruit. The record for smallest seed is still held by certain orchids in the Orchidaceae.

I have reported 5 species of Wolffia in the Jepson Flora Of California: W. borealis, W. brasiliensis, W. arrhiza, W. columbiana, and W. globosa. They are all minute flowering plants, but W. globosa is definitely the smallest. I have no idea how this Asian species got into Abeja Pond. Possibly it was introduced by birds from locations in Lake Hodges or the San Dieguito River, San Diego County. Or maybe someone dumped their tropical fish into the water. In Thailand it is called "khai-nam" which means water eggs. It is gathered for food and eaten like "green rice."

Left: Close-up views of Wolffia globosa
in San Diego County.

How Small Are Wolffia Plants?

Candy sprinkles compared with a thimble filled with wolffia plants (mostly Wolffia columbiana). The average diameter of a globose wolffia plant body is about 1/25th of an inch (1 mm). To appreciate their minute size, wolffia plants are comparable in size to the multicolored candy sprinkles used for decorating cakes and cookies.

Mixed population of Wolffia globosa (WG), W. columbiana (WC) and W. borealis (WB) all collected in the Lake Hodges-San Dieguito River of San Diego County. The smallest plants are W. globosa. Scanned from 35mm Kodochrome Transparecy.

I collected one minute, non-budding Wolffia plant body in a clump of duckweeds along the shore. It compares favorably with W. globosa that I have collected & photographed in California, including San Diego County. Although it is transparent green, the small size and green dorsal layer rules out the more common W. columbiana. I will search for additional Wolffia plants this fall 2020.

The single Wolffia globosa I collected at Abeja Pond produced a minute daughter plant at its basal end. This process is called budding. Duckweeds (Lemna) produce daughter plants by budding along their lateral margins. The result of budding is exponential asexual population growth and astronomical numbers of Lemna and Wolffia. Duckweeds (including Wolffia) also have sexual reproduction by apetalous flowers, fruits and seeds. Because the male and female floral organs mature at different times on individual plants, they require cross pollination. In Wolffia the flower-bearing plant bodies can literally be piled on top of each other by the wind.

Wolffia plants have the fastest population growth rate of any member of the kingdom Plantae. Under optimal conditions, a single plant of the Indian species Wolffia microscopica may reproduce vegetatively by budding every 30 hours. One minute plant could mathematically give rise to one nonillion plants or 1 x 1030 (one followed by 30 zeros) in about four months, with a spherical volume roughly equivalent to the size of the planet earth! Note: This is purely a mathematical projection and in reality could never happen!

Exponential Population Growth Equation: N = Noert

number in initial
population (No)
growth rate (r)
(decimal value)
length of time (t)
(same units as r)
number in final
population (N)
1 Wolffia
125 days
2.5154386709191598e +30
or 2.515 x 1030
*This would be a ball of wolffia plants roughly equivalent to the plant Earth!

The minute, globose plant body with flattened, green, dorsal surface that floats above water surface compares with Wolffia globosa from Florida quite well. I will try to grow this microscopic flowering plant and see if it develops a budding plant at its basal end. The only Wolffia species that rivals W. globosa in minuteness is the Australian species W. angusta (see following Wolffia links).

I collected another minute Wolffia globosa on 28 Oct 2020. It was hidden among a mass of Lemna minuta along the shore of Abeja Pond. The W. borealis in full bloom was collected in the San Dieguito River below Lake Hodges Dam, also in San Diego County.

Some Of Wayne's Duckweed Pages

  Subfamily Lemnoideae Within The Araceae  
Images Of Asian Species: Wolffia globosa
World's Smallest Flowering Plants
Wolffia: World's Smallest Fruits