Floral organogenesis of Titanotrichum oldhamii (Hemsl.) Soler., the only species in the genus and endemic to East Asia, was observed under SEM. We found that the development of calyx, corolla and androecium belong...Floral organogenesis of Titanotrichum oldhamii (Hemsl.) Soler., the only species in the genus and endemic to East Asia, was observed under SEM. We found that the development of calyx, corolla and androecium belongs to pentamerous pattern. They come respectively from primordia of calyx, corolla and androecium, and all differentiated from the flower primordium. The zygomorphism of corolla and androecium is derived from quicker growth of the upper lip of corolla and delay in development of the staminode. Initiation of sepal primordia and their development are not consistent in order; the order of initiation is from adaxial central primordium, abaxial two primordia and finally lateral two primordia, while the order of development is first adaxial central sepal, lateral two and finally abaxial two. Sepals are valvate in flower bud. Initiation of corolla lobe primordia and their development are consistent in order, i.e. first abaxial central lobe (central lobe of the lower lip), lateral two (lateral two lobes of the lower lip) and finally adaxial two (two lobes of the upper lip). The aestivation of corolla is imbricate, and the order from outside to inside is the central lobe of the lower lip, lateral two of the lower lip, and finally two of the upper lip or lateral two lobes of the lower lip, two of the upper lip and central one of the lower lip. Stamen primordia are alternate to the corolla lobe primordia, with the anterior two primordia later than the posterior two in initiation; staminode primordium is simultaneous with the posterior two in initiation, but smaller, and opposite to the adaxial carpel (upper lip of stigma). Compared to the patterns of floral organogenesis of Rehmannia (Scrophulariaceae), Whytockia and Rhynchoglossum (Gesneriaceae), the present authors found that the floral organogenesis is diverse and does not form two distinct patterns among these four genera. Based on the results we tend to consider that the conventional demarcation between the Scrophulariaceae and Gesneriaceae using number of ovary locules (two vs one) and placentation (axile vs parietal) is questionable.展开更多
Floral organogenesis and development of Przewalskia tangutica Maxim. endemic to China and Hyoscyamus niger L., which belong to the tribe Hyoscyameae (Solanaceae), were studied using scanning electron microscope. They ...Floral organogenesis and development of Przewalskia tangutica Maxim. endemic to China and Hyoscyamus niger L., which belong to the tribe Hyoscyameae (Solanaceae), were studied using scanning electron microscope. They have three common characters of floral organ initiation and development: 1) initiation of the floral organs in the two species follows Hofmeister's rule; 2) the mode of corolla tube development belongs to the 'late sympetaly' type; 3) primordia of the floral appendages initiated in a pentamerous pattern and acropetal order. But initiation of the calyx-lobe primordia showed different modes in these two species. The calyx-lobe primordia of H. niger have simultaneously whorled initiation, while those of P. tangutica have helical initiation, but the five calyx-lobe primordia form a ring after all five calyx-lobe primordia occur. The systematic significance of the present results in the genera Hyoscyamus and Przewalskia is discussed in this paper.展开更多
The floral organogenesis and development of Delavaya toxocarpa Franch. （Sapindaceae） were studied trader scanning electron microscope and light microscope to determine its systematic position within Sapindaceae. Flo...The floral organogenesis and development of Delavaya toxocarpa Franch. （Sapindaceae） were studied trader scanning electron microscope and light microscope to determine its systematic position within Sapindaceae. Flowers arise in terminal thyrses. The sepal primordia initiate in a spiral （2/5） sequence, which are not synchronous. The five petal primordia initiate almost synchronously and alternate with sepal primordia. Eight stamens initiate almost simultaneously and their differentiation precedes that of the petals. The last formed petal and one stamen initiate from a common primordium. Mature stamens curve inwards and cover the ovary in bud. The gynoecium begins as a hemispheric primordium on which two carpellary lobes arise simultaneously. Later in development a single gynocium is formed with two locules and two ovules per locule. Floral morphology suggests a closer affinity with Sapindaceae, although certain features of floral ontogenesis are similar to those observed in certain members of the former Hippocastanaceae, such as Handeliodendron.展开更多
文摘Floral organogenesis of Titanotrichum oldhamii (Hemsl.) Soler., the only species in the genus and endemic to East Asia, was observed under SEM. We found that the development of calyx, corolla and androecium belongs to pentamerous pattern. They come respectively from primordia of calyx, corolla and androecium, and all differentiated from the flower primordium. The zygomorphism of corolla and androecium is derived from quicker growth of the upper lip of corolla and delay in development of the staminode. Initiation of sepal primordia and their development are not consistent in order; the order of initiation is from adaxial central primordium, abaxial two primordia and finally lateral two primordia, while the order of development is first adaxial central sepal, lateral two and finally abaxial two. Sepals are valvate in flower bud. Initiation of corolla lobe primordia and their development are consistent in order, i.e. first abaxial central lobe (central lobe of the lower lip), lateral two (lateral two lobes of the lower lip) and finally adaxial two (two lobes of the upper lip). The aestivation of corolla is imbricate, and the order from outside to inside is the central lobe of the lower lip, lateral two of the lower lip, and finally two of the upper lip or lateral two lobes of the lower lip, two of the upper lip and central one of the lower lip. Stamen primordia are alternate to the corolla lobe primordia, with the anterior two primordia later than the posterior two in initiation; staminode primordium is simultaneous with the posterior two in initiation, but smaller, and opposite to the adaxial carpel (upper lip of stigma). Compared to the patterns of floral organogenesis of Rehmannia (Scrophulariaceae), Whytockia and Rhynchoglossum (Gesneriaceae), the present authors found that the floral organogenesis is diverse and does not form two distinct patterns among these four genera. Based on the results we tend to consider that the conventional demarcation between the Scrophulariaceae and Gesneriaceae using number of ovary locules (two vs one) and placentation (axile vs parietal) is questionable.
文摘Floral organogenesis and development of Przewalskia tangutica Maxim. endemic to China and Hyoscyamus niger L., which belong to the tribe Hyoscyameae (Solanaceae), were studied using scanning electron microscope. They have three common characters of floral organ initiation and development: 1) initiation of the floral organs in the two species follows Hofmeister's rule; 2) the mode of corolla tube development belongs to the 'late sympetaly' type; 3) primordia of the floral appendages initiated in a pentamerous pattern and acropetal order. But initiation of the calyx-lobe primordia showed different modes in these two species. The calyx-lobe primordia of H. niger have simultaneously whorled initiation, while those of P. tangutica have helical initiation, but the five calyx-lobe primordia form a ring after all five calyx-lobe primordia occur. The systematic significance of the present results in the genera Hyoscyamus and Przewalskia is discussed in this paper.
基金supported by South China Botanical Garden, Chinese Academy of Sciences.
文摘The floral organogenesis and development of Delavaya toxocarpa Franch. （Sapindaceae） were studied trader scanning electron microscope and light microscope to determine its systematic position within Sapindaceae. Flowers arise in terminal thyrses. The sepal primordia initiate in a spiral （2/5） sequence, which are not synchronous. The five petal primordia initiate almost synchronously and alternate with sepal primordia. Eight stamens initiate almost simultaneously and their differentiation precedes that of the petals. The last formed petal and one stamen initiate from a common primordium. Mature stamens curve inwards and cover the ovary in bud. The gynoecium begins as a hemispheric primordium on which two carpellary lobes arise simultaneously. Later in development a single gynocium is formed with two locules and two ovules per locule. Floral morphology suggests a closer affinity with Sapindaceae, although certain features of floral ontogenesis are similar to those observed in certain members of the former Hippocastanaceae, such as Handeliodendron.
