Saccharina japonica, Laminaria japonica, L. saccharina, Ecklonia kurome  昆 布 Kūn bù- "Similar to the Japanese word Konbu",   Kombu, Ecklonia, Japanese Sea Tangle   Family: Laminariaceae     
PART USED: Thallus (algae leaf)- harvested in Summer or Autumn.
Also called 海带 Hǎi dài
Most kombu is from the species Saccharina japonica (Laminaria japonica). It is an edible kelp, extensively cultivated on ropes in the seas of Japan and Korea. Over 90% of Japanese kombu is cultivated, mostly in Hokkaidō, but also as far south as the Seto Inland Sea with the development of cultivation technology today.
Nature: Cold      FLAVOR:  Salty, (can soften hardness),[3,6] bitter    CHANNEL: Kidney, Stomach, Liver
FUNCTIONS
GROUP: Antitussive and Expectorant Clearing- Hot Phlegm
1. Reduces Phlegm and soften hard lumps,[1,3,6] and subcutaneous nodules of  Phlegm.[1,2,4]  Eliminate phlegm. Clearing Hot Phlegm.
3. Promotes diuresis,[3,6] reducing edema.[7] Promotes moisturization.[1] Because this action is weak it is used as an adjunctive herb for edema and leg Qi.[6]
4. Lower blood pressure.
INDICATIONS
1. Lumps- Enlarged lymph nodes.[1,6] Tumours.[1] Congestion, painful and/or swelling in testicles.[1] Regular consumption of Kelp at meals relieves goitre,[3] and hypertension. Subcutaneous nodules. Difficulty in swallowing.[3] Local swelling of thyroid gland. Lymphatic tuberculosis.[3] Congestion in chest caused by Phlegm.[1,6]
2. Edema.[1,2,3,4] Scrofula. Beriberi. Obesity.
3. Vaginal discharge.[3] Swelling and pain of the testes.[3]
4. Hicupping.[3]
CONTRAINDICATIONS: Spleen deficiency with loose stools.[4] Spleen/Stomach deficiency,[6] and bad for persons with hidden Dampness in body, bad for skinny people.[2] Pregnant women and people with weak digestion.[3]
COMBINATIONS
COMPARISONS- Hai zao and Kun bu
Similarities: Haizao and Kunbu are salty and cold, and enter the liver, lung, and kidney meridians. Both can clear heat, transform phlegm, soften hardness, and dissipate nodules. They can also promote urination and reduce edema. In clinical practice, they are often used together to treat nodules such as goiter and scrofula.[5]
Differences- Hai zao is stronger in transforming phlegm and dissipating nodules, and it is more suitable for treating goiter and scrofula. Kunbu is stronger in softening hardness and reducing congealed blood; it is more suitable for treating liver-spleen enlargement, liver cirrhosis, and tumors.[5]
PREPARATIONS: Decoction.  Dried seaweed 5-10 g.[1,2] 4.5 - 15 g.[6] To make kelp powder, roast the kelp and grind into powder.[3] Good quality is thick.
Decoction 9-15g.[4]  Boil or powder.[1]

Research: One experiment shows kelp is effective for hypothryroidism due to iodine deficiency; kelp also temporatily inhibits the basal metabolic rate in hyperthyroidism, and improves the symptoms for a short duration.[3] Another experiment indicates that kelp reduces blood pressure, asthma attacks, and coughing.[3] Prolonged consumption of kelp will cause weight loss.[3]
NOTES:
According to Chinese medicine, seaweeds have a salty taste that is an indication that the material can disperse phlegm accumulation, particularly as it forms soft masses, include goitre, the thyroid swelling that indicates severe iodine deficiency.[5]
Types of seaweed used in chinese herbs
Saccharina (Genus) - Laminaria (kelp), a brown algae Kun bu
Sargassum (Genus) - a brown algae, as the source of Hai zao
Porphyra (Genus) - a red algae, as the source of  Zi cai
References
Inner Path can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.
Constituents
Laminaria: alinic acid, laminarin, laminine, inorganic salts- including those of potassium, iodine, iron, and calcium, mannitol, carotene, protein, riboflavin, vitamin C.[1]
Ecklonia: alginic acid, protein, mannitol, potassium, iodine.[1]
References
[1] Chinese Herbal Medicine Materia Medica- Dan Bensky and Andrew Gamble- Eastland Press 1986 Seattle Washington ISBN 0-939616-15-7