Common name: Floating Bur-reed
Scientific name: Sparganium angustifolium 線葉黑三棱
Genus: Sparganium 黑三棱屬*
Family: Typhaceae 香蒲科, cattail family
Note: Sparganium 黑三棱屬 is placed in Sparganiaceae 黑三棱科 in Cronquist system, of 1981. The APG II system, of 2003 (unchanged from the APG system, 1998), also recognizes this family. By the APG III system of 2009, Sparganium had been found to be fairly closely related to Typha 香蒲屬, and so was placed with that genus in family Typhaceae 香蒲科.
Origin: native
Date: 7th Aug (at 745m elevation) &13th Aug (at another location at 665m elevation)
[178] A large cluster of floating bur-reed in this lake of 745m elevation. It could be found in clear, nutrient-poor, organic-rich, acid or neutral upland lakes; to 1005m.
[179] Parts of the leaves, some bracts of the inflorescence are floating on the lake, with inflorescence erecting from the water surface.
[177] Rhizomatous perennial. Stem long, slender, submerged or floating, to 100cm. Note those floating on the water surface of the above photo are either the long leaves or the bracts of the inflorescence. Stem are those part of the plant below the inflorescence and are seen under the water.
[171_1] An individual plant in the middle of the above photo. It is fruiting already and male flower heads withered and dropped off. Bracts (Br) are leaf-like, erect from the water surface first and then bend and float on the water. Leaves (L) are even longer and the upper parts of the leaves are floating on the water. Leaf base (Lb) could be seen in the above photo.
[171_2] Photo cropped above to show the inflated leaf base (Lb) with sheathing. (St: stem) Leaves are alternate and basal.
[173] Another plant with cropped photo below.
[173_1] Cropped photo showing the leaf without keel or midrib.(vs stem leaves keeled at base in Sparganium emersum 小黑三棱, unbranched bur-reed.) (Br: bract; L: leaf; St:stem).
Stems are erect, green and smooth.
[082] (at another location at 665m elevation) It is perhaps the environment here is cooler than those plants found at 745m above and so male and female flowers are still flowering now.
[085] (at another location) Leaves all floating on the surface, linear, 30-80cm x 2-4mm (4 feet long, to ¼ inch (2 to 6 mm) wide), hairless, toothless, flat on the upper surface, flat to convex on the lower.
(vs stem leaves triangular in section in Sparganium emersum 小黑三棱, unbranched bur-reed.)
Surfaces are green, the lower surface with green parallel veins and no keel. Leaves become more translucent below the water's surface.
[086] (at another location) A plant without flower. The leaves are so long that the upper part of them are floating on the water surface whereas the lower part are submerged and in upright position.
[097] (at another location) A lot of flowering plants with both male and female heads could be seen emerged from the water.
[100] (at another location) An individual plant in the middle of the photo above, with flowering inflorescence rising from the water surface.
[097_1] (at another location) Flowering stems rise slightly above the surface of the water. Inflorescence unbranched. (vs inflorescence branched in Sparganium erectum 直立黑三棱, branched bur-reed. )
The lowest bracts (leaf-like bract of lowest female head, i.e the red arrow above) is more than 10cm long and is 2.5-4 times as long as inflorescence (the blue arrow above). (vs leaf-like bract of lowest female head is less than 10cm long and is barely longer than the inflorescence in Sparganium natans 矮黑三棱, least bur-reed.)
(M1, M2 are male heads whereas F1, F2 and F3 are female heads.)
[093] (at another location) Male and female flower heads could be seen in this individual.
[093_1] (at another location) Round (male and female) flower heads in a spike-like arrangement at the top of the (main) stem, with separate male and female flower heads on the same plant (monoecious). (vs 6-9 male heads on branches in Sparganium erectum 直立黑三棱, branched bur-reed.)
2-3 (2-4) stalkless male heads (2 above, M1 & M2), usually crowded and appearing as a single elongated terminal head. (vs 6-9 male heads on branches in Sparganium erectum 直立黑三棱, branched bur-reed.) (vs 4-7 male heads in Sparganium erersum 小黑三棱, branched bur-reed.) (vs 1 male head in Sparganium natans 矮黑三棱, least bur-reed.)
Each male head covered in dozens of petal-less flowers with 3 or more yellow-tipped white stamens. Male flower heads turn brown, wither and drop off after pollen release, the naked part of the stem usually persisting for a time but eventually also withering away;
2-4 (2-5) female heads (3 above, F1, F2 & F3). are slightly larger than the males, and are single in the axils of leaf-like bracts, the upper head(s) stalkless, the lowest head(s) stalked with the stalk at least partially fused to the stem so the head looks attached to the stem above the axil (known as supra-auxillary 腋上生的).
[166] Male flower heads are withering but female flower head could still be seen flowering right now for this individual.
[166_1] Photo cropped above to show the female flower head. Individual flowers have a single style at the tip of a green ovary and are surrounded by 3-6 scale-like tepals (petals with similar sepals) that lack a darker spot near the tip (could not be seen in the above photo, possibly need to dissect the flower head to examine them). (vs tepals dark-tipped in Sparganium erectum 直立黑三棱, branched bur-reed.)
Note the bracts (the leaf-like structure left to the female flower bead) inflated at base.
[164] As it is said before that these plants are found higher in altitude and perhaps the environment is warmer, flowers had finished. Male heads withered and fell apart whereas the female flower head is fruiting right now.
[164_1] Female flower head turns into fruit now. Female flower heads form densely packed seed heads that expand up to about 1 inch (to 30 mm) diameter, the plump 飽滿的, spiky head maturing from light green to reddish-brown. Fruiting heads up to ~1 inch (3 cm) diameter, fruit with straight beaks shorter than the body.
Note the lowest head(s) stalked with the stalk at least partially fused to the stem (see the blue arrows above) so the head looks attached to the stem above the axil (known as supra-auxillary 腋上生的).
