The largest single-stem plants are all members of the conifer division.
By volume and mass, the largest tree is the Giant Sequoia (Sequoiadendron giganteum). They grow to an average height of 70 ? 85 m (230 ? 280 ft) and 5 ? 7 m (16 ? 23 ft) in diameter. Specimens have been recorded to be up to 93.6 m (307 ft) in height and (not the same individual) 8.85 m (29 ft) in diameter; the largest individual is the General Sherman tree, with a volume of 1,489 m?.
Although not so large in volume, the closely related Coast Redwood (Sequoia sempervirens) is taller, reaching a maximum height of 115.25 m (380.3 ft). These trees dwarf any other non-communal organism, as even the largest Blue Whales are likely to weigh one-sixteenth as much as a large Giant Sequoia or Coast Redwood.
- Algae. The largest form of algae is the huge form of seaweed from the northwestern Pacific known as the giant kelp (Macrocystis pyrifera). The record-sized stem from one of these just slightly exceeded 60 m (200 ft).
- Liverworts (Marchantiophyta). The largest species of liverwort is a New Zealand species, Schistochila appendiculata. The top size of this species is 1.1 m (3.6 ft) long, a diameter of 2.5 cm (1 in) and a stem length of 10 cm (4 in).
- Mosses (Bryophyta). The world's largest moss is Dawsonia superba, of New Zealand. This species can be 50 cm (20 in) tall.
- Horsetails (Equisetophyta). The largest of horsetails is the species Equisetum myriochaetum, of central Mexico. The biggest specimen known was 8 m (26.4 ft) tall and had a diameter of 2.5 cm (1 in).
- Ferns (Pteridophyta). The largest species of fern is the majestic King Fern (Angiopteris evecta), of the Australasian area. A single frond of this plant can exceed 5 m (16.5 ft) in height.
- Conifers (Pinophyta). Besides the giant Sequoiadendron and Sequoia already mentioned, the conifers also include the largest tree by circumference in the world, the Montezuma Cypress (Taxodium mucronatum). The thickest recorded tree, found in Mexico, is called ?rbol del Tule, with a circumference of 35.87 m (118.3 ft) and a diameter of 11.42 m (37.5 ft) at 1.5 m (5 ft) above ground level.
- Cycads (Cycadophyta). The largest species of cycad is Hope's Cycad (Lepidozamia hopei), of the Queensland area of Australia. The largest examples of this species have been over 17 m (56 ft) tall and have had a diameter of over 50 cm (20 in).
- Flowering plants (Magnoliophyta). This is the most diverse and numerous division of plants, with upwards of 400,000 species. Typically the largest flowering plant (angiosperm) has been considered Eucalyptus regnans, which can reach heights of 92 m (304 ft).
Stands of trees connected to a single root system (a single organism genetically) may be considered the largest organisms, and the largest flowering plants. The largest known such colony is a male Aspen in Utah, nicknamed Pando (Populus tremuloides), which is estimated to weigh in at approximately 6,000 tonnes (6,615 tons).
Another form of flowering plant that rivals Pando as the largest organism on earth in breadth, if not mass, is the giant marine plant, Posidonia oceanica, discovered in the Mediterranean Sea near the Balearic Islands, Spain. Its length is about 8 km (4.3 miles). Although this plant has not yet proved itself to be a single organism, all the samples do have the same DNA. It is also thought to be the oldest living organism in the world since its estimated age is about 100,000 years.
Other records among flowering plants include, the title of largest flower, which belongs to the species Rafflesia arnoldii. One of these flowers can reach a diameter of 1 m (3.3 ft) and weigh up to 11 kg (24 lb). The largest unbranched inflorescence, resembling (but no qualifying as) a giant flower, belongs to the Titan Arum (Amorphophallus titanum), reaching almost 3 m (10 ft) in height. The absolute largest inflorescence, at up to 8 m (26.5 ft) long, is borne by the Talipot palm (Corypha umbraculifera) of India.