Udumbara Flower (Youtan Poluo) Controversy
A rarely seen Buddhist flower, Udumbara or Youtan Poluo, which is said to blossom every 3,000 years, was first discovered in South Korea. The earliest Udumbara found in Korea was in July 1997 on a golden brass Tathagata sculpture in a Buddhist temple in Kyungki-Do. There were 24 Udumbara measuring 0.1 inches found on the chest of a Tathagata (Buddha) sculpture. In May 2005, Udumbara was found in a thousand year-old temple, Sumi Zen Temple, located in Gyeongju City, Korea. Kim, a Zen Master, from the temple said he didn't know what they were when he first found them. He tried to wipe them off but they stayed. He observed them and realized they were plants with blossoms, stems and roots. On June 8, 2007, west of Seoul, 22 Udumbara were found on a name plate in a garden located on the roof of a district court next to the director's office. The same day, about a dozen Udumbara blossomed on a window in a university in Noryangjin-dong, Dongjak-gu, Seoul. On June 8, 48 Udumbara were found west of Kwangju City. The flowers were subsequently found in Mainland China, Hong Kong, Taiwan, Vietnam, Indonesia, USA and elsewhere.
In Buddhist scriptures, the Udumbara blossoms every three thousand years and is believed by Buddhists to be a sign of an overwhelming blessing and good fortune. What does this alleged blossoming of Udumbara flowers mean? Can this be the sign of imminent arrival of a great buddhist king or just another bull shit? You be the judge!
The myth that surrounds this plant called the Youtan Poluo or Udumbara is that the flowers have clung and grown on wide varieties of surface.
The alleged mystical udumbara flowers
Rare Udumbara Flowers Blossom in Korea

Mystical flower found in buddha sculpture This is the earliest Udumbara found in Korea in July 1997 on a golden brass Tathagata sculpture in a Buddhist temple in Kyungki-Do.
References: www.buddhistchannel.tv
baike.baidu.com (Chinese)
Google translation
toutiao.com (Chinese)
Image source and Reference:
www.youtube.com
alt
alt
www.youtube.com (Chinese)
A cluster of Udumbara flowers blossoming in Indonesia

A cluster of Udumbara flowers blossoming on a leaf and on a rope surrounding an orchid tree on the third floor of the home of a Falun Gong practitioner in Medan, North Sumatra.
Image source and Reference: www.clearwisdom.net
www.clearwisdom.net
The alleged udumbara flowers have been seen blossoming on Buddha statues

The alleged udumbara flowers were seen blossoming on Buddha statues in a thousand year-old temple, Sumi Zen Temple in Korea, 2005
Image source: Multiple sources
References: theepochtimes.com
beforeitsnews.com
Most believe these alleged mystical udumbara flowers are actually green lacewing eggs.
Green lacewing eggs
These are documented pictures of green lacewing eggs in academic publications.
Green lacewing eggs

Green lacewing eggs
Green lacewing eggs are rather unique and easy to recognize. The egg is a green to white capsule less than 1/32 inch suspended by a long thread (1/4-inch long) typically found on the underside of vegetable plant leaves, laid singly and in clusters.
Image source: ext100.wsu.edu
lacewing Egg on a leaf (Chrysoperla carnea)

Egg on a leaf - green lacewing (Chrysoperla carnea)
Image source: www.forestryimages.org
Eggs on apple tree. - Chrysoperla sp. eggs

Eggs on apple tree. - Chrysoperla sp. eggs
Image source: bugguide.net
Additional image: commons.wikimedia.org
These pictures of authentic lacewing eggs were recirculated and mis-identified as the mystical udumbara flowers in many websites.
Alleged Udumbara Flower versus Green lacewing eggs
The following photos show lacewing eggs at different stage of hatching.
The egg of Chrysopa before and after hatching

The egg of Chrysopa before hatching (left) and after hatching (right)
Lacewing eggs hatching

Image source: baike.baidu.com
m.shenchuang.com
Lacewing eggs (After hatching)

Lacewing eggs (After hatching)
Image source: toutiao.com
These are the commonly used pictures to differentiate alleged mystical flowers from Lacewing eggs. I don't think they are convincing.
Rare Udumbara Flowers Blossom in Korea

Rare Udumbara Flowers Blossom in Korea
Image/Video source: www.youtube.com
Multiple sources
Udumbara Flower ?

Udumbara Flower ?
They are likely the stalked eggs of a lacewing (Family Chrysopidae). (www.flickr.com)
Image source: www.flickr.com
Multiple sources
Mysterious Flower Blooms Once Every 3,000 Years

Image/Video source: www.youtube.com
Udumbara Flowers Blossom

Udumbara Flowers Blossom (優曇婆羅花)
Image/Video source: www.youtube.com
Another Video: www.youtube.com
Real Udumbara Tree (Ficus), commonly known as Fig Tree
Ficus racemosa (syn. Ficus glomerata) is a species of plant in the family Moraceae. Popularly known as the Cluster Fig Tree, Indian Fig Tree or Goolar (Gular) Fig, this is native to Australia, Malaysia, South-East Asia and the Indian Subcontinent. It is unusual in that its figs grow on or close to the tree trunk, termed cauliflory. In India the tree and its fruit are called gular in the north and atti in the south. The fruits are a favourite staple of the common Indian macaque. It serves as a food plant for the caterpillars of the butterfly the Two-brand Crow (Euploea sylvester) of northern Australia. (Wikipedia)
In Buddhism, uḍumbara refers to the tree, flower and fruit of the Ficus racemosa (Ficus glomerata).
The Bodhi Tree (Sanskrit: बोधि) was a large and very old sacred fig tree (Ficus religiosa) located in Bodh Gaya, Bihar, India, under which Siddhartha Gautama, the spiritual teacher later known as Buddha, is said to have attained enlightenment.
(Wikipedia: Bodhi Tree)
Ficus is a genus of about 850 species of woody trees, shrubs, vines, epiphytes and hemiepiphytes in the family Moraceae. Collectively known as fig trees or figs.
A fig "fruit" is derived from a specially adapted type of inflorescence (an arrangement of multiple flowers). In this case, it is an involuted, nearly closed receptacle with many small flowers arranged on the inner surface. Thus the actual flowers of the fig are unseen unless the fig is cut open. In Chinese the fig is called wú huā guǒ (Chinese: 無花果), "fruit without flower". In Bengali, where the common fig is called dumur, it is referenced in a proverb: tumi jeno dumurer phool hoe gele ("You have become [invisible like] the dumur flower"). (Wikipedia: Ficus)
This is probably the origin of the alleged mystical udumbara flowers. Since the flowers are hidden and not seen, it is safe to claim that they blossom every 3000 years.
Lion-tailed macaque feeding on fig fruits

Lion-tailed macaque feeding on on fig fruits
Image source: commons.wikimedia.org
The third eastern gopura, with strangler fig

White Fig or Strangler Fig (Ficus virens), enclosing the eastern entrance to The third eastern gopura.
East side of the third eastern gopura, Temple of Ta Som at Angkor in Cambodia.
Image source: commons.wikimedia.org
Reference: Wikipedia Ta Som
The Mahabodhi Tree at the Sri Mahabodhi Temple in Bodh Gaya.


Mahabodhi tree Mahabodhi tree
Mahabodhi tree (Sacred Fig) next to the Mahabodhi Temple, the spot where Siddhartha Gautama, the Buddha, attained enlightenment.
The Mahabodhi Tree at the Sri Mahabodhi Temple in Bodh Gaya.


Left: 1810 picture of a small temple beneath the Bodhi tree, Bodh Gaya.
Right: The Mahabodhi tree in Bodhgaya today
The bodhi tree next to the Mahabodhi Temple in Bodh Gaya, the spot where Siddhartha Gautama, the Buddha, attained enlightenment, is a fig tree.
Fig tree roots overgrowing a sandstone Buddha statue

Fig tree roots overgrowing a sandstone Buddha statue, near Wat Maha That in Ayutthaya province, Thailand
Image source: commons.wikimedia.org
References: Wikipedia Ficus (Fig trees)
Ayutthaya Kingdom
Ficus stuhlmannii wrapped around Bridelia micrantha

Ficus stuhlmannii wrapped around Bridelia micrantha
Image source: commons.wikimedia.org
Reference: Wikipedia Ficus stuhlmannii
The fig wasp’s life cycle is typified in the caprifig (Ficus carica sylvestris)

The fig wasp’s life cycle is typified in the caprifig (Ficus carica sylvestris)
Mislabelled as Udumbara tree and flowers

Mislabelled as Udumbara tree and flowers
This has been called the rare Udumbara flowers in multiple websites. I think they are wrong. It is labeled as "Phaleria clerodendron" at the www.flickr.com, and I agree that it is one of the Phaleria species.
A blossoming tree trunk (Phaleria)

A blossoming tree trunk (Phaleria)
See also other similar or related images:
Phaleria capitata Image source Reference: Wikipedia
Phaleria clerodendron Image source and Refernce
Phaleria clerodendron
Phaleria clerodendron
Phaleria clerodendron
Phaleria octandra
Phaleria_capitata