Fossil plants with attached organs are rare but provide important data in the study of plant evolution. Eoflora herba is an entire plant, about 27 cm long, including a rhizomatous axis bearing roots and shoots. It has five unbranched fertile shoots and a main shoot that has 3 younger sterile branches, 8 fertile branches, and a terminal fertile axis. The nine reproductive axes mature basipetally and resemble a cymose inflorescence. Fertile shoots have helically arranged filiform leaves with multiple fine vascular bundles in the petiole and blade that is deeply dissected into lobes and further divided into linear to slightly spatulate segments. Fertile shoots end in stamen clusters subtending carpels or fruits, all helically arranged. Stamen clusters commonly have two stamens with very short filaments attached to a short stalk, alternately or in pairs. Anthers have two loculi with four chambers. Some anthers contain in situ pollen. Each fruit, on a short stipe, is developed from a conduplicate carpel with 7-8 ovules commonly. The axial section with stamens attached has internodal elongation, conceptually blurring the distinction between flowers and inflorescences, and suggesting that this generalized floral structure has the evolutionary potential to shorten into flowers or elongate into inflorescences. Eoflora herba is found from the Jiulongsong Member of the Yixian Formation, which is stratigraphically below the bed from which Archaefructus was found, and is estimated 133 mya based on the ages of the above and underlying volcanic rocks. The fossil supports the Herbaceous Origin Hypothesis by showing that at least these earliest angiosperms were herbaceous. The filiform leaves are so significantly different from the expected form for basal angiosperms that dispersed leaves would be simply identified as ferns. They have cuticles only on the leaves at floral level, suggesting that Eoflora was an emersed aquatic plant.

Key words: aquatic herb, bisexual flower evolution, earliest angiosperm fossil, Eoflora of Archaemagnoliidae, herbaceous origin hypothesis, Yixian Formation.